Optimize one-byte string's toUpperCase.

tests/corelib/corelib.status

Index: tests/corelib/corelib.status
diff --git a/tests/corelib/corelib.status b/tests/corelib/corelib.status
index 46fa91665beb5c57f0d349b6b87274aee915f764..f11ff6ecbf1be1d5fdfc6242dc7d67bbd360c92c 100644
--- a/tests/corelib/corelib.status
+++ b/tests/corelib/corelib.status
@@ -52,6 +52,8 @@ compare_to2_test: Fail    # Bug 4018
 
 symbol_test/01: Fail, Pass # bug 11669
 
+string_case_test/01: Fail # Bug 18061
+
 [ $compiler == none && $runtime != dartium && $runtime != drt && $runtime != ContentShellOnAndroid ]
 symbol_test/02: MissingCompileTimeError # bug 11669
 symbol_test/03: MissingCompileTimeError # bug 11669
@@ -111,6 +113,21 @@ list_as_map_test: Pass, Slow # TODO(kasperl): Please triage.
 [ $compiler == dart2js && ($runtime == d8 || $runtime == chrome || $runtime == drt || $runtime == safari) ]
 string_trimlr_test/none: Fail # Bug in v8. Fixed in v8 r19222, 2014-02-10.
 
+[ $compiler == dart2js && ($runtime == d8 || $runtime == drt) ]
+string_case_test/02: Fail, OK  # Bug in our version of V8.
+
+[ $compiler == dart2js && ($runtime == ie9 || $runtime == ie10) ]
+string_case_test/01: Fail, OK  # Bug in IE.
+string_case_test/02: Fail, OK  # Bug in IE.
+
+[ $compiler == dart2js && ($runtime == ff || $runtime == jsshell) ]
+string_case_test/01: Fail, OK  # Bug in Firefox.
+
+[ $compiler == dart2js && $runtime == dartium ]
+string_case_test/02: Fail, OK  # Bug in dartium version of V8.
+string_case_test/03: Fail, OK  # Bug in dartium version of V8.
+
+
 [ $compiler == dart2js && $checked ]
 map_test: Crash # Issue 17829