dart2dart: Logical operators and related rewrite rules in dart_tree.

sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart

Index: sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart
diff --git a/sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart b/sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart
index aeaee9f883d5a2cf1841a0d15f307ad5c74a1651..d0a3af2ad08b06ded5441fe04c924980853a3380 100644
--- a/sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart
+++ b/sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart
@@ -235,8 +235,10 @@ class DartBackend extends Backend {
         compiler.tracer.traceCompilation(element.name, null, compiler);
         compiler.tracer.traceGraph('Tree builder', definition);
         treeElements = new TreeElementMapping(element);
-        new tree.TreeRewriter().apply(definition);
+        new tree.StatementRewriter().rewrite(definition);
         compiler.tracer.traceGraph('Tree rewriter', definition);
+        new tree.LogicalRewriter().rewrite(definition);
+        compiler.tracer.traceGraph('Logical rewriter', definition);
         node = dart_codegen.emit(element, treeElements, definition);
       }
       return new ElementAst(node, treeElements);