Clean up warnings.

sdk/lib/_internal/compiler/implementation/ssa/codegen.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.
 
 part of ssa;
 
 class SsaCodeGeneratorTask extends CompilerTask {
 
   final JavaScriptBackend backend;
 
@@ skipping 933 matching lines @@
           currentContainer = oldContainer;
           body = unwrapStatement(body);
           loop = new js.While(jsCondition, body);
         }
         break;
       case HLoopBlockInformation.DO_WHILE_LOOP:
         if (info.initializer != null) {
           generateStatements(info.initializer);
         }
         js.Block oldContainer = currentContainer;
-        js.Statement body = new js.Block.empty();
+        js.Block body = new js.Block.empty();
         // If there are phi copies in the block that jumps to the
         // loop entry, we must emit the condition like this:
         // do {
         //   body;
         //   if (condition) {
         //     phi updates;
         //     continue;
         //   } else {
         //     break;
         //   }
         // } while (true);
         HBasicBlock avoidEdge = info.end.successors[0];
-        js.Statement updateBody = new js.Block.empty();
+        js.Block updateBody = new js.Block.empty();
         currentContainer = updateBody;
         assignPhisOfSuccessors(avoidEdge);
         bool hasPhiUpdates = !updateBody.statements.isEmpty;
         currentContainer = body;
         if (hasPhiUpdates || !isConditionExpression || info.updates != null) {
           wrapLoopBodyForContinue(info);
         } else {
           visitBodyIgnoreLabels(info);
         }
         if (info.updates != null) {
@@ skipping 2132 matching lines @@
   if (leftType.canBeNull() && rightType.canBeNull()) {
     if (left.isConstantNull() || right.isConstantNull() ||
         (leftType.isPrimitive() && leftType == rightType)) {
       return '==';
     }
     return null;
   } else {
     return '===';
   }
 }