Move catch prediction into frontend.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 74ec944c194da43429a9e7d7df30b0a98ee8bf29..0bea2544fa1b3dcf49c93ebbbbb16e06c6f03e44 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -734,8 +734,7 @@ class Isolate {
 
   // Tries to predict whether an exception will be caught. Note that this can
   // only produce an estimate, because it is undecidable whether a finally
-  // clause will consume or re-throw an exception. We conservatively assume any
-  // finally clause will behave as if the exception were consumed.
+  // clause will consume or re-throw an exception.
   enum CatchType { NOT_CAUGHT, CAUGHT_BY_JAVASCRIPT, CAUGHT_BY_EXTERNAL };
   CatchType PredictExceptionCatcher();