Enforce strict equalities with JSHint
Add strict equalities in src/core/parser.js
Add strict equalities in src/core/stream.js
Merge pull request #5125 from Snuffleupagus/strict-equalities-src-core-3

Add strict equalities in src/core/* (part 3)
Merge pull request #5122 from timvandermeij/jshint-strict-equalities

Enforce strict equalities with JSHint