pass library files not directories to analysis server

editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/analysis/AnalysisServer.java

 /*
  * Copyright 2012 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 121 matching lines @@
     IdleListener[] newListeners = new IdleListener[oldLen + 1];
     System.arraycopy(idleListeners, 0, newListeners, 0, oldLen);
     newListeners[oldLen] = listener;
     idleListeners = newListeners;
   }
 
   /**
    * Analyze the specified library, and keep that analysis current by tracking any changes. Also see
    * {@link Context#resolve(File, ResolveCallback)}.
    * 
-   * @param file the library file (not <code>null</code>)
+   * @param libraryFile the library file (not <code>null</code>)
    */
-  public void analyze(File file) {
-    if (!file.isAbsolute()) {
-      throw new IllegalArgumentException("File path must be absolute: " + file);
+  public void analyze(File libraryFile) {
+    if (!libraryFile.isAbsolute()) {
+      throw new IllegalArgumentException("File path must be absolute: " + libraryFile);
+    }
+    if (libraryFile.isDirectory()) {
+      throw new IllegalArgumentException("Cannot analyze a directory: " + libraryFile);
     }
     synchronized (queue) {
-      if (!libraryFiles.contains(file)) {
-        libraryFiles.add(file);
+      if (!libraryFiles.contains(libraryFile)) {
+        libraryFiles.add(libraryFile);
         // Append analysis task to the end of the queue so that any user requests take precedence
         queueAnalyzeContext();
       }
     }
   }
 
   /**
    * Called when a file or directory has been added or removed or file content has been modified.
    * Use {@link #discard(File)} if the file or directory content should no longer be analyzed.
    * 
@@ skipping 564 matching lines @@
       if (task instanceof AnalyzeLibraryTask) {
         AnalyzeLibraryTask libTask = (AnalyzeLibraryTask) task;
         cacheWriter.writeString(libTask.getRootLibraryFile().getPath());
       } else if (task instanceof AnalyzeContextTask) {
         cacheWriter.writeString(ANALYZE_CONTEXT_TAG);
       }
     }
     cacheWriter.writeString(END_QUEUE_TAG);
   }
 }