Add for-of Crankshaft support

src/x64/full-codegen-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1221 matching lines @@
 
   // var iterator = iterable[@@iterator]()
   VisitForAccumulatorValue(stmt->assign_iterator());
 
   // As with for-in, skip the loop if the iterator is null or undefined.
   __ CompareRoot(rax, Heap::kUndefinedValueRootIndex);
   __ j(equal, loop_statement.break_label());
   __ CompareRoot(rax, Heap::kNullValueRootIndex);
   __ j(equal, loop_statement.break_label());
 
-  // Convert the iterator to a JS object.
-  Label convert, done_convert;
-  __ JumpIfSmi(rax, &convert);
-  __ CmpObjectType(rax, FIRST_SPEC_OBJECT_TYPE, rcx);
-  __ j(above_equal, &done_convert);
-  __ bind(&convert);
-  __ push(rax);
-  __ InvokeBuiltin(Builtins::TO_OBJECT, CALL_FUNCTION);
-  __ bind(&done_convert);
-
   // Loop entry.
   __ bind(loop_statement.continue_label());
 
   // result = iterator.next()
   VisitForEffect(stmt->next_result());
 
   // if (result.done) break;
   Label result_not_done;
   VisitForControl(stmt->result_done(),
                   loop_statement.break_label(),
                   &result_not_done,
                   &result_not_done);
   __ bind(&result_not_done);
 
+  PrepareForBailoutForId(stmt->BodyId(), NO_REGISTERS);
+
   // each = result.value
   VisitForEffect(stmt->assign_each());
 
   // Generate code for the body of the loop.
   Visit(stmt->body());
 
-  // Check stack before looping.
-  PrepareForBailoutForId(stmt->BackEdgeId(), NO_REGISTERS);
+  // Loop.
   EmitBackEdgeBookkeeping(stmt, loop_statement.continue_label());
   __ jmp(loop_statement.continue_label());
 
   // Exit and decrement the loop depth.
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
   __ bind(loop_statement.break_label());
   decrement_loop_depth();
 }
 
 
@@ skipping 3632 matching lines @@
   *context_length = 0;
   return previous_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64