[turbofan] Re-enable webkit test that no longer fail.

test/webkit/webkit.status

 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 17 matching lines @@
 [
 [ALWAYS, {
   # Flaky tests.
   # BUG(v8:2989).
   'dfg-inline-arguments-become-double': [PASS, FAIL],
   'dfg-inline-arguments-become-int32': [PASS, FAIL],
   'dfg-inline-arguments-reset': [PASS, FAIL],
   'dfg-inline-arguments-reset-changetype': [PASS, FAIL],
   # TODO(turbofan): We run out of stack earlier on 64-bit for now.
   'fast/js/deep-recursion-test': [PASS, NO_VARIANTS],
-  # TODO(bmeurer,svenpanne): Investigate test failure.
-  'fast/js/toString-number': [SKIP],
 }],  # ALWAYS
 ['mode == debug', {
   # Too slow in debug mode.
   'dfg-int-overflow-in-loop': [SKIP],
   'dfg-double-vote-fuzz': [SKIP],
   'reentrant-caching': [SKIP],
   'sort-large-array': [SKIP],
   # Too slow with --enable-slow-asserts.
   'array-iterate-backwards': [SKIP],
 }],  # 'mode == debug'
@@ skipping 41 matching lines @@
   # Tests taking too long
   'fast/js/excessive-comma-usage': [SKIP]
 }],  # 'gc_stress == True'
 
 ['gc_stress == True and mode == debug', {
   # Skip tests that timeout.
 }],  # 'gc_stress == True and mode == debug'
 
 ##############################################################################
 ]