Remove Map.groupBy
Map.toList() returns List of Pairs instead of List of Entries.
Map.filter() returns Map instead of List of Entries
Breaking change. Map operations revisited.
Recover test for mutable List variable and move it to ListSpecificTests
collection.toMap(selector)
Map.Entry.toPair
Remove map iteration from ListSpecificTest - JS fails, but it is irrelevant to test.
Use LinkedHashMap everywhere to preserve order.
Add StdLibMapTest, fix naming to convention StdLib* tests.
Split tests into platform-independent and JVM.
Minor: assert -> assertTrue
Moved MutableMap.set from Maps.kt to MapsJVM.kt to avoid ambiguity when compile MapTest.kt by JS backend.
JS stdlib: allowed use null as key and value in Map implementations. Added tests for using null in Set and Map implementations.
Fix assertion arguments.
Use different file for navigation test because of test framework limitation.
Tests for map functions.
Merge pull request #495 from JetBrains/rr/stdlib_maps

Map-related fixes and improvements in stdlib.