only remap break/continue when inside a loop

lib/6to5/transformation/transformers/es6/block-scoping.js

@@ -315,7 +315,7 @@ var loopVisitor = {
       return context.skip();
     }
 
-    if (node && !node.label) {
+    if (node && !node.label && state.isLoop) {
       if (t.isBreakStatement(node)) {
         if (t.isSwitchCase(parent)) return;
 
@@ -352,6 +352,7 @@ LetScoping.prototype.checkLoop = function () {
     hasContinue: false,
     hasReturn:   false,
     hasBreak:    false,
+    isLoop:      !!this.loopParent
   };
 
   traverse(this.block, loopVisitor, this.scope, state);