[stubs] Port LoadScriptContextFieldStub and StoreScriptContextFieldStub to TurboFan.

src/crankshaft/hydrogen.h

Index: src/crankshaft/hydrogen.h
diff --git a/src/crankshaft/hydrogen.h b/src/crankshaft/hydrogen.h
index 2d6b5ea3b61a9b82e148d04f8b658129922ed0a1..d01958456d7a64ef3361d25f2d68fe6e9d854593 100644
--- a/src/crankshaft/hydrogen.h
+++ b/src/crankshaft/hydrogen.h
@@ -1860,7 +1860,7 @@ class HGraphBuilder {
 
   HInstruction* BuildGetNativeContext(HValue* closure);
   HInstruction* BuildGetNativeContext();
-  HInstruction* BuildGetScriptContext(int context_index);
+
   // Builds a loop version if |depth| is specified or unrolls the loop to
   // |depth_value| iterations otherwise.
   HValue* BuildGetParentContext(HValue* depth, int depth_value);