[crankshaft] Fix crash when case labels inline endless loops

test/mjsunit/regress/regress-crbug-551287.js

Index: test/mjsunit/regress/regress-crbug-551287.js
diff --git a/test/mjsunit/compiler/regress-491578.js b/test/mjsunit/regress/regress-crbug-551287.js
similarity index 58%
copy from test/mjsunit/compiler/regress-491578.js
copy to test/mjsunit/regress/regress-crbug-551287.js
index c27570456c31e9a191fe1f4f1ea17b80f29de98e..a85deef4bb0445308c26123e7b27d0d0a22ec8a8 100644
--- a/test/mjsunit/compiler/regress-491578.js
+++ b/test/mjsunit/regress/regress-crbug-551287.js
@@ -4,12 +4,14 @@
 
 // Flags: --allow-natives-syntax
 
-function foo(x) {
-  if (x === undefined) return;
-  while (true) {
-    while (1 || 2) { }
-    f();
+function f() { do { } while (true); }
+
+function boom(x) {
+  switch(x) {
+    case 1:
+    case f(): return;
   }
 }
-%OptimizeFunctionOnNextCall(foo);
-foo();
+
+%OptimizeFunctionOnNextCall(boom)
+boom(1);