Change int.fromEnvironment in VM to use same code as int.parse.

runtime/lib/string.cc

 // Copyright (c) 2011, 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.
 
 #include "vm/bootstrap_natives.h"
 
 #include "include/dart_api.h"
 #include "vm/exceptions.h"
 #include "vm/dart_api_impl.h"
 #include "vm/isolate.h"
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/symbols.h"
 #include "vm/unicode.h"
 
 namespace dart {
 
 DEFINE_NATIVE_ENTRY(String_fromEnvironment, 3) {
   GET_NON_NULL_NATIVE_ARGUMENT(String, name, arguments->NativeArgAt(1));
   GET_NATIVE_ARGUMENT(String, default_value, arguments->NativeArgAt(2));
   // Call the embedder to supply us with the environment.
   Dart_EnvironmentCallback callback = isolate->environment_callback();
   if (callback != NULL) {
     Dart_Handle result = callback(Api::NewHandle(isolate, name.raw()));
-    if (Dart_IsError(result)) {
+    if (Dart_IsString(result)) {
+      const Object& value =
+          Object::Handle(isolate, Api::UnwrapHandle(result));
+      return Symbols::New(String::Cast(value));
+    } else if (Dart_IsError(result)) {
       const Object& error =
           Object::Handle(isolate, Api::UnwrapHandle(result));
       Exceptions::ThrowArgumentError(
           String::Handle(
               String::New(Error::Cast(error).ToErrorCString())));
-    } else if (Dart_IsString(result)) {
-      const Object& value =
-          Object::Handle(isolate, Api::UnwrapHandle(result));
-      return Symbols::New(String::Cast(value));
     } else if (!Dart_IsNull(result)) {
       Exceptions::ThrowArgumentError(
           String::Handle(String::New("Illegal environment value")));
     }
   }
   return default_value.raw();
 }
 
 
 DEFINE_NATIVE_ENTRY(StringBase_createFromCodePoints, 1) {
@@ skipping 250 matching lines @@
       ? String::Handle(OneByteString::New(length_value, Heap::kNew))
       : String::Handle(TwoByteString::New(length_value, Heap::kNew));
   NoGCScope no_gc;
 
   uint16_t* data_position = reinterpret_cast<uint16_t*>(codeUnits.DataAddr(0));
   String::Copy(result, 0, data_position, length_value);
   return result.raw();
 }
 
 }  // namespace dart