Make the strict-mode calling convention for contextual calls the default one.

src/x64/ic-x64.cc

Index: src/x64/ic-x64.cc
diff --git a/src/x64/ic-x64.cc b/src/x64/ic-x64.cc
index 886d50be9c2ff624d7c652bec8f0280fb7f9201f..cea2b80cf0e3e2d5667d25d69ab4bad1800f8109 100644
--- a/src/x64/ic-x64.cc
+++ b/src/x64/ic-x64.cc
@@ -998,7 +998,7 @@ void CallICBase::GenerateMiss(MacroAssembler* masm,
 
     // Patch the receiver on the stack.
     __ bind(&global);
-    CallStubCompiler::FetchGlobalProxy(masm, rdx, rdi);
+    __ LoadRoot(rdx, Heap::kUndefinedValueRootIndex);
     __ movq(args.GetReceiverOperand(), rdx);
     __ bind(&invoke);
   }