Add string.trimLeft/trimRight.

tests/corelib/corelib.status

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 [ $compiler == dart2dart]
 bool_from_environment2_test: Skip
 bool_from_environment_default_value_test: Skip
 bool_from_environment_test: Skip
 int_from_environment2_test: Skip
 int_from_environment3_test: Skip
@@ skipping 93 matching lines @@
 [ $compiler == dart2js && $runtime == ie9 ]
 string_base_vm_test: Fail # BUG(3304): Maybe this doesn't time out?
 list_test: Fail # IE doesn't support typed data.
 shuffle_test: Fail # IE doesn't support typed data.
 
 [ $compiler == dart2js && $runtime == chromeOnAndroid ]
 list_as_map_test: Pass, Slow # TODO(kasperl): Please triage.
 
 [ $compiler == dart2js && ($runtime == firefox || $runtime == safari || $runtime == chrome || $runtime == drt) ]
 
+[ $compiler == dart2js && ($runtime == d8 || $runtime == chrome || $runtime == drt || $runtime == safari) ]
+string_trimlr_test/none: Fail # Bug in v8. Fixed in v8 r19222, 2014-02-10.

[floitsch, 2014/03/12 12:34:29]

If it was just a v8 bug we could ignore it and wait for the fix to reach stable.
Since it is also present in safari we should change our library function to work
with it.

[Lasse Reichstein Nielsen, 2014/03/12 14:54:50]

The change would be not using the JS trim function, which would likely cost in
performance. It's not a new issue with this change, it was just not tested
before, but the existing trim function has the same problem.

I think it's a rare occurrence to actually trim U+200B, and therefore not likely
to be a problem in practice (although it is rather annoying). We generate code
that is valid for ES5, it's just that Safari (and V8 for a little while yet) are
not ES5 compliant.

V8 changing behavior could be the thing that makes JSC look at it again. I'd say
we keep it as-is for now, and see if it causes any problems.

+
 [ $compiler == dart2dart ]
 compare_to2_test: Fail # inherited from VM
 unicode_test: Fail # inherited from VM
 
 [ $compiler == dart2dart && $minified ]
 error_stack_trace1_test: Fail # Fails in minified mode, test depends on method names.
 
 [ $compiler == dartanalyzer ]
 symbol_test/02: Fail
 symbol_test/03: Fail
@@ skipping 21 matching lines @@
 iterable_element_at_test: StaticWarning, OK # Test generates errors on purpose.
 num_clamp_test: StaticWarning, OK # Test generates errors on purpose.
 string_test: StaticWarning, OK # Test generates error on purpose.
 
 [ $compiler == dart2js && $runtime == safari ]
 list_test/01: Fail # Safari bug: Array(-2) seen as dead code.
 
 [ $runtime == ie9 || $runtime == ie10 ]
 num_parse_test: RuntimeError  # Issue 15316
 num_parse_test/01: RuntimeError  # Issue 15316