Code change:
<ins> [ { "c": "// from https://flutter.dev/", "t": "source.dart comment.line.double-slash.dart", "r": { "dark_plus": "comment: #6A9955", "light_plus": "comment: #008000", "dark_vs": "comment: #6A9955", "light_vs": "comment: #008000", "hc_black": "comment: #7CA668" } }, { "c": "import", "t": "source.dart meta.declaration.dart keyword.other.import.dart", "r": { "dark_plus": "keyword: #569CD6", "light_plus": "keyword: #0000FF", "dark_vs": "keyword: #569CD6", "light_vs": "keyword: #0000FF", "hc_black": "keyword: #569CD6" } }, { "c": " ", "t": "source.dart meta.declaration.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "'package:flutter/material.dart'", "t": "source.dart meta.declaration.dart string.interpolated.single.dart", "r": { "dark_plus": "string: #CE9178", "light_plus": "string: #A31515", "dark_vs": "string: #CE9178", "light_vs": "string: #A31515", "hc_black": "string: #CE9178" } }, { "c": ";", "t": "source.dart meta.declaration.dart punctuation.terminator.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "void", "t": "source.dart storage.type.primitive.dart", "r": { "dark_plus": "storage.type: #569CD6", "light_plus": "storage.type: #0000FF", "dark_vs": "storage.type: #569CD6", "light_vs": "storage.type: #0000FF", "hc_black": "storage.type: #569CD6" } }, { "c": " ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "main", "t": "source.dart entity.name.function.dart", "r": { "dark_plus": "entity.name.function: #DCDCAA", "light_plus": "entity.name.function: #795E26", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "entity.name.function: #DCDCAA" } }, { "c": "() ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "async", "t": "source.dart keyword.control.dart", "r": { "dark_plus": "keyword.control: #C586C0", "light_plus": "keyword.control: #AF00DB", "dark_vs": "keyword.control: #569CD6", "light_vs": "keyword.control: #0000FF", "hc_black": "keyword.control: #C586C0" } }, { "c": " {", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "  ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "runApp", "t": "source.dart entity.name.function.dart", "r": { "dark_plus": "entity.name.function: #DCDCAA", "light_plus": "entity.name.function: #795E26", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "entity.name.function: #DCDCAA" } }, { "c": "(", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "    ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "MaterialApp", "t": "source.dart support.class.dart", "r": { "dark_plus": "support.class: #4EC9B0", "light_plus": "support.class: #267F99", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "support.class: #4EC9B0" } }, { "c": "(", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "      debugShowCheckedModeBanner", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": ":", "t": "source.dart keyword.operator.ternary.dart", "r": { "dark_plus": "keyword.operator: #D4D4D4", "light_plus": "keyword.operator: #000000", "dark_vs": "keyword.operator: #D4D4D4", "light_vs": "keyword.operator: #000000", "hc_black": "keyword.operator: #D4D4D4" } }, { "c": " ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "false", "t": "source.dart constant.language.dart", "r": { "dark_plus": "constant.language: #569CD6", "light_plus": "constant.language: #0000FF", "dark_vs": "constant.language: #569CD6", "light_vs": "constant.language: #0000FF", "hc_black": "constant.language: #569CD6" } }, { "c": ",", "t": "source.dart punctuation.comma.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "      home", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": ":", "t": "source.dart keyword.operator.ternary.dart", "r": { "dark_plus": "keyword.operator: #D4D4D4", "light_plus": "keyword.operator: #000000", "dark_vs": "keyword.operator: #D4D4D4", "light_vs": "keyword.operator: #000000", "hc_black": "keyword.operator: #D4D4D4" } }, { "c": " ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "Scaffold", "t": "source.dart support.class.dart", "r": { "dark_plus": "support.class: #4EC9B0", "light_plus": "support.class: #267F99", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "support.class: #4EC9B0" } }, { "c": "(", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "        body", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": ":", "t": "source.dart keyword.operator.ternary.dart", "r": { "dark_plus": "keyword.operator: #D4D4D4", "light_plus": "keyword.operator: #000000", "dark_vs": "keyword.operator: #D4D4D4", "light_vs": "keyword.operator: #000000", "hc_black": "keyword.operator: #D4D4D4" } }, { "c": " ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "MyApp", "t": "source.dart support.class.dart", "r": { "dark_plus": "support.class: #4EC9B0", "light_plus": "support.class: #267F99", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "support.class: #4EC9B0" } }, { "c": "()", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": ",", "t": "source.dart punctuation.comma.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "      )", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": ",", "t": "source.dart punctuation.comma.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "    )", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": ",", "t": "source.dart punctuation.comma.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "  )", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": ";", "t": "source.dart punctuation.terminator.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "}", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "class", "t": "source.dart keyword.declaration.dart", "r": { "dark_plus": "keyword: #569CD6", "light_plus": "keyword: #0000FF", "dark_vs": "keyword: #569CD6", "light_vs": "keyword: #0000FF", "hc_black": "keyword: #569CD6" } }, { "c": " ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "MyApp", "t": "source.dart support.class.dart", "r": { "dark_plus": "support.class: #4EC9B0", "light_plus": "support.class: #267F99", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "support.class: #4EC9B0" } }, { "c": " ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "extends", "t": "source.dart keyword.declaration.dart", "r": { "dark_plus": "keyword: #569CD6", "light_plus": "keyword: #0000FF", "dark_vs": "keyword: #569CD6", "light_vs": "keyword: #0000FF", "hc_black": "keyword: #569CD6" } }, { "c": " ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "StatefulWidget", "t": "source.dart support.class.dart", "r": { "dark_plus": "support.class: #4EC9B0", "light_plus": "support.class: #267F99", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "support.class: #4EC9B0" } }, { "c": " {", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "  ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "@override", "t": "source.dart storage.type.annotation.dart", "r": { "dark_plus": "storage.type: #569CD6", "light_plus": "storage.type: #0000FF", "dark_vs": "storage.type: #569CD6", "light_vs": "storage.type: #0000FF", "hc_black": "storage.type: #569CD6" } }, { "c": "  ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "_MyAppState", "t": "source.dart support.class.dart", "r": { "dark_plus": "support.class: #4EC9B0", "light_plus": "support.class: #267F99", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "support.class: #4EC9B0" } }, { "c": " ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "createState", "t": "source.dart entity.name.function.dart", "r": { "dark_plus": "entity.name.function: #DCDCAA", "light_plus": "entity.name.function: #795E26", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "entity.name.function: #DCDCAA" } }, { "c": "() ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "=>", "t": "source.dart keyword.operator.closure.dart", "r": { "dark_plus": "keyword.operator: #D4D4D4", "light_plus": "keyword.operator: #000000", "dark_vs": "keyword.operator: #D4D4D4", "light_vs": "keyword.operator: #000000", "hc_black": "keyword.operator: #D4D4D4" } }, { "c": " ", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "_MyAppState", "t": "source.dart support.class.dart", "r": { "dark_plus": "support.class: #4EC9B0", "light_plus": "support.class: #267F99", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "support.class: #4EC9B0" } }, { "c": "()", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": ";", "t": "source.dart punctuation.terminator.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } }, { "c": "}", "t": "source.dart", "r": { "dark_plus": "default: #D4D4D4", "light_plus": "default: #000000", "dark_vs": "default: #D4D4D4", "light_vs": "default: #000000", "hc_black": "default: #FFFFFF" } } ] </ins>  No newline at end of file

Related discussion:
text: An easy way to test it's working is to disable the Dart/Flutter extensions (accept the prompt to reload), then open a Dart file. You'll now still get syntax highlighting (note: you won't get analysis or much other editor functionality, that requires the Dart extension). <img width="650" alt="Screenshot 2021-06-14 at 15 52 25" src="https://user-"
Yeah I just did, and it works great :-)