[dart2dart] Optionally cut types in variable declarations:

lib/compiler/implementation/dart_backend/renamer.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Renames only top-level elements that would let to ambiguity if not renamed.
  * TODO(smok): Make sure that top-level fields are correctly renamed.
  */
 void renamePlaceholders(
     Compiler compiler,
     PlaceholderCollector placeholderCollector,
     Map<Node, String> renames,
     Map<LibraryElement, String> imports,
-    bool minify) {
+    bool minify,
+    bool cutDeclarationTypes) {
   final Map<LibraryElement, Map<String, String>> renamed
       = new Map<LibraryElement, Map<String, String>>();
   final Set<String> usedTopLevelIdentifiers = new Set<String>();
   // TODO(antonm): we should also populate this set with top-level
   // names from core library.
   usedTopLevelIdentifiers.add('main'); // Never rename anything to 'main'.
 
   Generator topLevelGenerator =
       minify ? new MinifyingGenerator('ABCDEFGHIJKLMNOPQRSTUVWXYZ').generate
           : conservativeGenerator;
@@ skipping 68 matching lines @@
                   || usedTopLevelIdentifiers.contains(name)
                   || usedLocalIdentifiers.contains(name)
                   || memberIdentifiers.contains(name));
       usedLocalIdentifiers.add(nextId);
       renameNodes(placeholder.nodes, (_) => nextId);
     }
   });
   sortedForEach(placeholderCollector.privateNodes, (library, nodes) {
     renameNodes(nodes, (node) => rename(library, node.source.slowToString()));
   });
+  if (cutDeclarationTypes) {
+    for (DeclarationTypePlaceholder placeholder in
+         placeholderCollector.declarationTypePlaceholders) {
+      renames[placeholder.typeNode] = placeholder.canOmitType ? '' : 'var';
+    }
+  }
 }
 
 typedef String Generator(String originalName, bool isForbidden(String name));
 
 /** Always tries to return original identifier name unless it is forbidden. */
 String conservativeGenerator(
     String originalName, bool isForbidden(String name)) {
   String newName = originalName;
   while (isForbidden(newName)) {
     newName = 'p_$newName';
@@ skipping 28 matching lines @@
     int length = alphabet.length;
     StringBuffer resultBuilder = new StringBuffer();
     while (index >= length) {
       resultBuilder.add(alphabet[index % length]);
       index ~/= length;
     }
     resultBuilder.add(alphabet[index]);
     return resultBuilder.toString();
   }
 }