dart2js fails language/built_in_identifier_prefix_test

[peter-ahe-google]

FAILED: dart2js-d8 release_ia32 language/built_in_identifier_prefix_test
Expected: pass
Actual: fail
Unexpected compile-time error.

stdout:
tests/language/built_in_identifier_prefix_test.dart:45:12: unexpected token '_abstract'
abstract.A _abstract = new abstract.A();
           ^^^^^^^^^
Error: Compilation failed.

stderr:
test.dart: Compilation failed (step 1 of 2), exit code 1

Compilation command: xcodebuild/ReleaseIA32/dart2js --allow-mock-compilation --package-root=xcodebuild/ReleaseIA32/packages/ /Users/ahe/Dart/all/dart/tests/language/built_in_identifier_prefix_test.dart --out=/Users/ahe/Dart/all/dart/xcodebuild/ReleaseIA32/generated_tests/dart2js-d8/tests_language_built_in_identifier_prefix_test/out.js

Command line: xcodebuild/ReleaseIA32/d8 /Users/ahe/Dart/all/dart/xcodebuild/ReleaseIA32/generated_tests/dart2js-d8/tests_language_built_in_identifier_prefix_test/out.js

[kasperl]

Added TriageForM5 label.

[kasperl]

Removed TriageForM5 label.

[sgjesse]

Also fails on dart2dart

[peter-ahe-google]

Marked this as blocking #12967.

[kasperl]

Removed this from the Later milestone.
Added Oldschool-Milestone-Later label.

[kasperl]

Removed Oldschool-Milestone-Later label.

[peter-ahe-google]

Proposed fix in CL 2876813002.