Improve error message for over qualified constructor names.

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

Index: compiler/java/com/google/dart/compiler/parser/CompletionHooksParserBase.java
===================================================================
--- compiler/java/com/google/dart/compiler/parser/CompletionHooksParserBase.java	(revision 418)
+++ compiler/java/com/google/dart/compiler/parser/CompletionHooksParserBase.java	(working copy)
@@ -18,7 +18,7 @@
  * <li>remember start positions to set source location information on AST
  * nodes
  * <li>provide an event mechanism that is useful for an IDE operating on code
- * being edited - for example, for error recovery or code completion 
+ * being edited - for example, for error recovery or code completion
  * </ol>
  * <p>
  * Every call to {@code beginFoo} must be balanced with exactly one call
@@ -90,7 +90,7 @@
 
   /**
    * Set the context the parser will use.
-   * 
+   *
    * @param ctx the {@link ParserContext} to use
    */
   public CompletionHooksParserBase(ParserContext ctx) {
@@ -145,6 +145,10 @@
     begin();
   }
 
+  protected void beginConstructorNamePart() {
+    begin();
+  }
+
   protected void beginContinueStatement() {
     begin();
   }
@@ -392,7 +396,7 @@
   /**
    * Terminates a grammatical structure, saving the source location in the
    * supplied AST node.
-   * 
+   *
    * @param <T> type of the AST node
    * @param result the AST node to return, if any - if it implements
    *     {@link HasSourceInfo}, the source location is set based on the
@@ -408,7 +412,7 @@
    * subcomponents of the AST. This may only be called within an active
    * {@link #begin()} call, which must still be terminated with either
    * {@link #done(Object)} or {@link #rollback()}.
-   * 
+   *
    * @param <T> type of the AST node
    * @param result the AST node to return - if it implements
    *    {@link HasSourceInfo}, the source location is set based on the