Fix a build issue w/ non-terminating builds and issues parsing dart:html.

compiler/java/com/google/dart/compiler/parser/DartParser.java

 // 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.
 
 package com.google.dart.compiler.parser;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.io.CharStreams;
 import com.google.dart.compiler.DartCompilationError;
@@ skipping 84 matching lines @@
 import com.google.dart.compiler.ast.LibraryUnit;
 import com.google.dart.compiler.ast.Modifiers;
 import com.google.dart.compiler.metrics.CompilerMetrics;
 import com.google.dart.compiler.parser.DartScanner.Location;
 import com.google.dart.compiler.parser.DartScanner.Position;
 import com.google.dart.compiler.util.Lists;
 
 import java.io.IOException;
 import java.io.Reader;
 import java.math.BigInteger;
+import java.net.URI;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 
 /**
  * The Dart parser. Parses a single compilation unit and produces a {@link DartUnit}.
  * The grammar rules are taken from Dart.g revision 557.
  */
@@ skipping 96 matching lines @@
                     String sourceCode,
                     boolean isDietParse,
                     Set<String> prefixes,
                     DartCompilerListener listener,
                     CompilerMetrics compilerMetrics) {
     super(new DartParserCommentsHelper.CommentParserContext(source, sourceCode, listener, compilerMetrics));
     this.source = source;
     this.sourceCode = sourceCode;
     this.isDietParse = isDietParse;
     this.prefixes = prefixes;
-    this.corelibParse = source != null && SystemLibraryManager.isDartUri(source.getUri());
+    
+    if (source != null) {
+      URI srcUri = source.getUri();
+      
+      if (srcUri.getScheme() == null) {
+        // TODO(devoncarew): find out when dart:html is being parsed as an external compilation unit
+        // (and our source == a DartSourceString). We're getting hundreds of parser errors because
+        // of native keywords in a file we don't think is a core library.
+        corelibParse = true;
+      } else {
+        corelibParse = SystemLibraryManager.isDartUri(srcUri);
+      }
+    } else {
+      corelibParse = false;
+    }
   }
 
   public static String read(Source source) throws IOException {
     return read(source.getSourceReader());
   }
 
   public static String read(Reader reader) throws IOException {
     try {
       return CharStreams.toString(reader);
     } finally {
@@ skipping 4399 matching lines @@
   }
 
   private void reportError(DartNode node, ErrorCode errorCode, Object... arguments) {
     reportError(new DartCompilationError(node, errorCode, arguments));
   }
 
   private boolean currentlyParsingToplevel() {
     return   !(isParsingInterface || isTopLevelAbstract || isParsingClass);
   }
 }