Bug 1382023 - Optimize better in presence of lookaround. r=jandem

This is a pull of v8 commit 8df7c2a21b07174c3704894ca1d149b2711dfa58,
reviewed at https://codereview.chromium.org/2777583003.

--HG--
extra : histedit_source : 62baef1128e57ddf77b715ffec727610ae7fb8ae

js/src/irregexp/RegExpEngine.cpp

@@ -633,9 +633,7 @@ ActionNode::FillInBMInfo(int offset,
     if (!bm->CheckOverRecursed())
         return false;
 
-    if (action_type_ == BEGIN_SUBMATCH) {
+    if (action_type_ != POSITIVE_SUBMATCH_SUCCESS) {
-        bm->SetRest(offset);
-    } else if (action_type_ != POSITIVE_SUBMATCH_SUCCESS) {
         if (!on_success()->FillInBMInfo(offset, budget - 1, bm, not_at_start))
             return false;
     }