CompileArrayPushCall should not use context register as a scratch.

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
diff --git a/src/x64/stub-cache-x64.cc b/src/x64/stub-cache-x64.cc
index bd723df653fe014dccccbe3e7efe60d4add426b2..9eea3477ab5801553ad073071e5db293a5ec0bfb 100644
--- a/src/x64/stub-cache-x64.cc
+++ b/src/x64/stub-cache-x64.cc
@@ -1488,8 +1488,8 @@ MaybeObject* CallStubCompiler::CompileArrayPushCall(Object* object,
       // the new element is non-Smi. For now, delegate to the builtin.
       Label no_fast_elements_check;
       __ JumpIfSmi(rdi, &no_fast_elements_check);
-      __ movq(rsi, FieldOperand(rdx, HeapObject::kMapOffset));
-      __ CheckFastObjectElements(rsi, &call_builtin, Label::kFar);
+      __ movq(rcx, FieldOperand(rdx, HeapObject::kMapOffset));
+      __ CheckFastObjectElements(rcx, &call_builtin, Label::kFar);
       __ bind(&no_fast_elements_check);
 
       ExternalReference new_space_allocation_top =