[Interpreter] Always store current context in the frames context slot.

src/interpreter/interpreter.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/interpreter.h"
 
 #include "src/code-factory.h"
 #include "src/compiler.h"
 #include "src/compiler/interpreter-assembler.h"
 #include "src/factory.h"
@@ skipping 798 matching lines @@
 void Interpreter::DoKeyedStoreICStrictWide(
     compiler::InterpreterAssembler* assembler) {
   Callable ic =
       CodeFactory::KeyedStoreICInOptimizedCode(isolate_, STRICT, UNINITIALIZED);
   DoKeyedStoreIC(ic, assembler);
 }
 
 
 // PushContext <context>
 //
-// Pushes the accumulator as the current context, and saves it in <context>
+// Saves the current context in <context>, and pushes the accumulator as the
+// new current context.
 void Interpreter::DoPushContext(compiler::InterpreterAssembler* assembler) {
   Node* reg_index = __ BytecodeOperandReg(0);
-  Node* context = __ GetAccumulator();
-  __ SetContext(context);
-  __ StoreRegister(context, reg_index);
+  Node* new_context = __ GetAccumulator();
+  Node* old_context = __ GetContext();
+  __ StoreRegister(old_context, reg_index);
+  __ SetContext(new_context);
   __ Dispatch();
 }
 
 
 // PopContext <context>
 //
 // Pops the current context and sets <context> as the new context.
 void Interpreter::DoPopContext(compiler::InterpreterAssembler* assembler) {
   Node* reg_index = __ BytecodeOperandReg(0);
   Node* context = __ LoadRegister(reg_index);
@@ skipping 1020 matching lines @@
   Node* index_reg = __ BytecodeOperandReg(0);
   Node* index = __ LoadRegister(index_reg);
   Node* result = __ CallRuntime(Runtime::kForInStep, index);
   __ SetAccumulator(result);
   __ Dispatch();
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8