Improve location information for some warnings/errors.

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

Index: compiler/java/com/google/dart/compiler/parser/AbstractParser.java
===================================================================
--- compiler/java/com/google/dart/compiler/parser/AbstractParser.java	(revision 512)
+++ compiler/java/com/google/dart/compiler/parser/AbstractParser.java	(working copy)
@@ -8,7 +8,6 @@
 import com.google.dart.compiler.DartCompilerErrorCode;
 import com.google.dart.compiler.ErrorCode;
 import com.google.dart.compiler.ast.DartNode;
-import com.google.dart.compiler.parser.DartScanner.Location;
 
 /**
  * Abstract base class for sharing common utility methods between implementation
@@ -91,13 +90,13 @@
    */
   protected void reportError(DartScanner.Position position, ErrorCode errorCode,
       Object... arguments) {
-    DartCompilationError dartError = new DartCompilationError(ctx.getTokenLocation(), errorCode,
-        arguments);
-    if (dartError.getStartPosition() <= lastErrorPosition) {
+    DartScanner.Location location = ctx.getTokenLocation();
+    if (location.getBegin().getPos() <= lastErrorPosition) {
       return;
     }
+    DartCompilationError dartError = new DartCompilationError(ctx.getSource(), location, errorCode,
+        arguments);
     lastErrorPosition = position.getPos();
-    dartError.setSource(ctx.getSource());
     ctx.error(dartError);
   }
 
@@ -129,8 +128,4 @@
     next();
     return result;
   }
-
-  public void error(Location location, DartCompilerErrorCode code, Object... arguments) {
-    ctx.error(new DartCompilationError(location, code, arguments));
-  }
 }