Clean up some warnings.

editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/editor/SpecificContentAssistExecutor.java

Index: editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/editor/SpecificContentAssistExecutor.java
===================================================================
--- editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/editor/SpecificContentAssistExecutor.java	(revision 11395)
+++ editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/editor/SpecificContentAssistExecutor.java	(working copy)
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, the Dart project authors.
+ * 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
@@ -50,12 +50,13 @@
    * @param categoryId the id of the proposal category to show proposals for
    */
   public void invokeContentAssist(final ITextEditor editor, String categoryId) {
-    Collection categories = fRegistry.getProposalCategories();
+    @SuppressWarnings("unchecked")
+    Collection<CompletionProposalCategory> categories = fRegistry.getProposalCategories();
     boolean[] inclusionState = new boolean[categories.size()];
     boolean[] separateState = new boolean[categories.size()];
     int i = 0;
-    for (Iterator it = categories.iterator(); it.hasNext(); i++) {
-      CompletionProposalCategory cat = (CompletionProposalCategory) it.next();
+    for (Iterator<CompletionProposalCategory> it = categories.iterator(); it.hasNext(); i++) {
+      CompletionProposalCategory cat = it.next();
       inclusionState[i] = cat.isIncluded();
       cat.setIncluded(cat.getId().equals(categoryId));
       separateState[i] = cat.isSeparateCommand();
@@ -69,8 +70,8 @@
       }
     } finally {
       i = 0;
-      for (Iterator it = categories.iterator(); it.hasNext(); i++) {
-        CompletionProposalCategory cat = (CompletionProposalCategory) it.next();
+      for (Iterator<CompletionProposalCategory> it = categories.iterator(); it.hasNext(); i++) {
+        CompletionProposalCategory cat = it.next();
         cat.setIncluded(inclusionState[i]);
         cat.setSeparateCommand(separateState[i]);
       }