Hydrogen: bailout when there is a throw statement in a non-effect context.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index b1b4dfc54cc68190faeeb9415ff9386ce7988e3d..35efe630aab242a6a88060021c55dd40c01df178 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -6753,10 +6753,12 @@ void HOptimizedGraphBuilder::VisitThrow(Throw* expr) {
   DCHECK(!HasStackOverflow());
   DCHECK(current_block() != NULL);
   DCHECK(current_block()->HasPredecessor());
-  // We don't optimize functions with invalid left-hand sides in
-  // assignments, count operations, or for-in.  Consequently throw can
-  // currently only occur in an effect context.
-  DCHECK(ast_context()->IsEffect());
+  if (!ast_context()->IsEffect()) {
+    // The parser turns invalid left-hand sides in assignments into throw
+    // statements, which may not be in effect contexts. We might still try
+    // to optimize such functions; bail out now if we do.
+    return Bailout(kInvalidLeftHandSideInAssignment);
+  }
   CHECK_ALIVE(VisitForValue(expr->exception()));
 
   HValue* value = environment()->Pop();