Refactor the dart api a bit:

runtime/vm/parser.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/parser.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/compiler_stats.h"
@@ skipping 2856 matching lines @@
     }
     const String& name = *CurrentLiteral();
     ConsumeToken();
     ExpectToken(Token::kRPAREN);
     ExpectToken(Token::kSEMICOLON);
     library_.SetName(name);
   }
 }
 
 
-Dart_Result Parser::CallLibraryTagHandler(Dart_LibraryTag tag,
+Dart_Handle Parser::CallLibraryTagHandler(Dart_LibraryTag tag,
                                    intptr_t token_pos,
                                    const String& url) {
   Dart_LibraryTagHandler handler = Isolate::Current()->library_tag_handler();
   if (handler == NULL) {
     ErrorMsg(token_pos, "no library handler registered");
   }
-  Dart_Result result = handler(tag,
+  Dart_Handle result = handler(tag,
                                Api::NewLocalHandle(library_),
                                Api::NewLocalHandle(url));
-  if (!Dart_IsValidResult(result)) {
-    ErrorMsg(token_pos, "library handler failed: %s",
-             Dart_GetErrorCString(result));
+  if (!Dart_IsValid(result)) {
+    ErrorMsg(token_pos, "library handler failed: %s", Dart_GetError(result));
   }
   return result;
 }
 
 
 void Parser::ParseLibraryImport() {
   while (CurrentToken() == Token::kIMPORT) {
     intptr_t import_pos = token_index_;
     ConsumeToken();
     ExpectToken(Token::kLPAREN);
@@ skipping 13 matching lines @@
       ConsumeToken();
       ExpectToken(Token::kCOLON);
       if (CurrentToken() != Token::kSTRING) {
         ErrorMsg("prefix expected");
       }
       prefix = CurrentLiteral()->raw();
       ConsumeToken();
     }
     ExpectToken(Token::kRPAREN);
     ExpectToken(Token::kSEMICOLON);
-    Dart_Result result = CallLibraryTagHandler(kCanonicalizeUrl,
+    Dart_Handle handle = CallLibraryTagHandler(kCanonicalizeUrl,
                                                import_pos,
                                                url);
-    Dart_Handle handle = Dart_GetResult(result);
     const String& canon_url = String::CheckedHandle(Api::UnwrapHandle(handle));
     // Lookup the library URL.
     Library& library = Library::Handle(Library::LookupLibrary(canon_url));
     if (library.IsNull()) {
       // Create a new library object and call the library tag handler.
       library = Library::New(canon_url);
       library.Register();
       // The tag handler expects the importing library as a parameter.
       CallLibraryTagHandler(kImportTag, import_pos, canon_url);
     }
@@ skipping 18 matching lines @@
     intptr_t source_pos = token_index_;
     ConsumeToken();
     ExpectToken(Token::kLPAREN);
     if (CurrentToken() != Token::kSTRING) {
       ErrorMsg("source url expected");
     }
     const String& url = *CurrentLiteral();
     ConsumeToken();
     ExpectToken(Token::kRPAREN);
     ExpectToken(Token::kSEMICOLON);
-    Dart_Result result = CallLibraryTagHandler(kCanonicalizeUrl,
+    Dart_Handle handle = CallLibraryTagHandler(kCanonicalizeUrl,
                                                source_pos,
                                                url);
-    Dart_Handle handle = Dart_GetResult(result);
     const String& canon_url = String::CheckedHandle(Api::UnwrapHandle(handle));
     CallLibraryTagHandler(kSourceTag, source_pos, canon_url);
   }
 }
 
 
 void Parser::ParseLibraryDefinition() {
   // Handle the script tag.
   if (CurrentToken() == Token::kSCRIPTTAG) {
     // Nothing to do for script tags except to skip them.
@@ skipping 4026 matching lines @@
 }
 
 
 void Parser::SkipNestedExpr() {
   const bool saved_mode = SetAllowFunctionLiterals(true);
   SkipExpr();
   SetAllowFunctionLiterals(saved_mode);
 }
 
 }  // namespace dart