Avoid printing braces for one-statement blocks in js-printer.

tests/compiler/dart2js/async_await_js_transform_test.dart

Index: tests/compiler/dart2js/async_await_js_transform_test.dart
diff --git a/tests/compiler/dart2js/async_await_js_transform_test.dart b/tests/compiler/dart2js/async_await_js_transform_test.dart
index 0f0873b7a1be42ac3b034215036b1a7d6cf0e5ff..72c6c09a3e28f311004d26cf270814dd4bdc7245 100644
--- a/tests/compiler/dart2js/async_await_js_transform_test.dart
+++ b/tests/compiler/dart2js/async_await_js_transform_test.dart
@@ -101,7 +101,7 @@ function(b) {
           case 8:
             // while condition
             __handler = 10;
-            inner: {
+            inner:
               while (true) {
                 __next = [6];
                 // goto finally
@@ -109,7 +109,6 @@ function(b) {
                 break __outer1;
                 break;
               }
-            }
             while (true) {
               __next = [1, 4];
               // goto finally
@@ -984,9 +983,9 @@ function(x, y, k) {
           break;
         case 14:
           // case
-          if (a) {
+          if (a)
             throw new Error();
-          } else {
+          else {
             // goto while condition
             __goto = 3;
             break;