Avoid repeated declaration of the same loop variable.

The following code:

void main() {
  int j = 0;
  for (int i = 0; i < 10; i++) {
    j++;
  }
}

would generate the following:

for (var j = 0, i = 0; i < 10; ) {
  j = j + 1;
  var i = i + 1;
}

with this change the 'var' in the body disappears.

R=ngeoffray@google.com
BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com//10471002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@8192 260f80e4-7a28-3924-810f-c04153c831b5

lib/compiler/compiler.dart

@@ -46,7 +46,5 @@ Future<String> compile(Uri script,
                                    options);
   compiler.run(script);
   String code = compiler.assembledCode;
-  Completer<String> completer = new Completer<String>();
-  completer.complete(code);
-  return completer.future;
+  return new Future.immediate(code);
 }

lib/compiler/implementation/dart2js.dart

@@ -164,9 +164,7 @@ void compile(List<String> argv) {
     dartBytesRead += source.length;
     sourceFiles[uri.toString()] =
       new SourceFile(relativize(cwd, uri), source);
-    Completer<String> completer = new Completer<String>();
-    completer.complete(source);
-    return completer.future;
+    return new Future.immediate(source);
   }
 
   void info(var message) {

lib/compiler/implementation/ssa/codegen.dart

@@ -468,9 +468,12 @@ class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
           declaredVariables.add(variableName);
           buffer.add("var ");
         }
-      } else if (!isGeneratingDeclaration()
-                 && !isVariableDeclared(variableName)) {
-        delayedVariablesDeclaration.add(variableName);
+      } else if (!isVariableDeclared(variableName)) {
+        if (!isGeneratingDeclaration()) {
+          delayedVariablesDeclaration.add(variableName);
+        } else {
+          declaredVariables.add(variableName);
+        }
       }
     } else if (!isVariableDeclared(variableName)) {
       declaredVariables.add(variableName);