[Interpreter] Move context chain search loop to handler

src/interpreter/interpreter-assembler.h

Index: src/interpreter/interpreter-assembler.h
diff --git a/src/interpreter/interpreter-assembler.h b/src/interpreter/interpreter-assembler.h
index 7e71cf220f07733a9491f6142e4725f9ceb3895d..1a78f543f7df3b08f32b88aaf8a9829b8006ccab 100644
--- a/src/interpreter/interpreter-assembler.h
+++ b/src/interpreter/interpreter-assembler.h
@@ -53,6 +53,10 @@ class InterpreterAssembler : public CodeStubAssembler {
   compiler::Node* GetContext();
   void SetContext(compiler::Node* value);
 
+  // Context at |depth| in the context chain starting at |context|
+  compiler::Node* GetContextAtDepth(compiler::Node* context,
+                                    compiler::Node* depth);
+
   // Number of registers.
   compiler::Node* RegisterCount();