KT-12275 Add JS optimization that transforms the following code

```
do {
    guard: {
        // do something
        break guard;
        // do something
    }
} while (condition)
```

to

```
do {
    // do something
    continue;
    // do something
} while (condition)
```

js/js.tests/test/org/jetbrains/kotlin/js/test/optimizer/DoWhileGuardEliminationTest.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.js.test.optimizer
+
+import org.junit.Test
+
+class DoWhileGuardEliminationTest : BasicOptimizerTest("do-while-guard-elimination") {
+    @Test fun simple() = box()
+
+    @Test fun innerContinue() = box()
+
+    @Test fun innerBreakInLoopWithoutLabel() = box()
+}