Force context allocation for variables in generator scopes.

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 142 matching lines @@
   FrameScope frame_scope(masm_, StackFrame::MANUAL);
 
   info->set_prologue_offset(masm_->pc_offset());
   __ push(rbp);  // Caller's frame pointer.
   __ movq(rbp, rsp);
   __ push(rsi);  // Callee's context.
   __ push(rdi);  // Callee's JS Function.
 
   { Comment cmnt(masm_, "[ Allocate locals");
     int locals_count = info->scope()->num_stack_slots();
+    // Generators allocate locals, if any, in context slots.
+    ASSERT(!info->function()->is_generator() || locals_count == 0);
     if (locals_count == 1) {
       __ PushRoot(Heap::kUndefinedValueRootIndex);
     } else if (locals_count > 1) {
       __ LoadRoot(rdx, Heap::kUndefinedValueRootIndex);
       for (int i = 0; i < locals_count; i++) {
         __ push(rdx);
       }
     }
   }
 
@@ skipping 4378 matching lines @@
   *context_length = 0;
   return previous_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64