Reland "Add basic crankshaft support for slow-mode for-in to avoid disabling optimizations"

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index a4451d7a0891bc2a07d8b9f3117053b1c644886c..16d8aecd50b0c17f8b4b3b835780cb0fed39ca3c 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -2260,6 +2260,9 @@ class HOptimizedGraphBuilder : public HGraphBuilder, public AstVisitor {
   void VisitLoopBody(IterationStatement* stmt,
                      HBasicBlock* loop_entry);
 
+  void BuildForInBody(ForInStatement* stmt, Variable* each_var,
+                      HValue* enumerable);
+
   // Create a back edge in the flow graph.  body_exit is the predecessor
   // block and loop_entry is the successor block.  loop_successor is the
   // block where control flow exits the loop normally (e.g., via failure of