Simplify and fix the rewriter

test/mjsunit/es6/completion.js

Index: test/mjsunit/es6/completion.js
diff --git a/test/mjsunit/es6/completion.js b/test/mjsunit/es6/completion.js
index 988e9709bb7a5c026823fbfd45b5bbeffb8cd73f..6bc7d47a025844d12a4fef62951dd4f1686bc88c 100644
--- a/test/mjsunit/es6/completion.js
+++ b/test/mjsunit/es6/completion.js
@@ -146,3 +146,10 @@ assertUndef(eval(
 assertUndef(eval("1; try{2; throwOnReturn();} catch(e){}"));
 assertUndef(eval("1; twoFunc();"));
 assertEquals(2, eval("1; with ( { a: 0 } ) { 2; }"));
+
+assertUndef(eval('a: while(true) { do { 0 } while(false); switch(1) { case 0: 1; case 1: break a; }; 0 }'));
+assertUndef(eval('a: while(true) { do { 0 } while(false); try {} finally { break a }; 0 }'));
+assertUndef(eval('a: while(true) { b: while(true) { 0; break b; }; switch(1) { case 1: break a; }; 2 }'));
+assertUndef(eval('a: while(true) { b: while(true) { 0; break b; }; while (true) { break a; }; 2 }'));
+assertUndef(eval('while (true) { 20; a:{ break a; }  with ({}) break; 30; }'));
+assertEquals(42, eval('a: while(true) { switch(0) { case 0: 42; case 1: break a; }; 33 }'));