Show errors reported for invalid setBreakpoint calls.

editor/tools/plugins/com.google.dart.tools.debug.core/src/com/google/dart/tools/debug/core/breakpoints/DartBreakpoint.java

 /*
  * Copyright (c) 2012, the Dart project authors.
  * 
  * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
  * 
  * http://www.eclipse.org/legal/epl-v10.html
  * 
  * Unless required by applicable law or agreed to in writing, software distributed under the License
  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
@@ skipping 126 matching lines @@
   }
 
   public String getFilePath() {
     try {
       return (String) getMarker().getAttribute(FILE_PATH);
     } catch (CoreException e) {
       return null;
     }
   }
 
+  public String getActualFilePath() {
+    IFile file = getFile();
+    if (file != null) {
+      return file.getLocation().toOSString();
+    }
+    return getFilePath();
+  }
+
   public int getLine() {
     IMarker marker = getMarker();
 
     if (marker != null) {
       return marker.getAttribute(IMarker.LINE_NUMBER, -1);
     }
 
     return -1;
   }
 
@@ skipping 35 matching lines @@
   public void updateLineNumber(int newLine) {
     try {
       getMarker().setAttribute(IMarker.LINE_NUMBER, newLine);
     } catch (CoreException e) {
       // We make a best effort to update the breakpoint's line.
 
     }
   }
 
 }