StubCallInterfaceDescriptor takes a context register.

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
diff --git a/src/x64/lithium-x64.h b/src/x64/lithium-x64.h
index ee7d160a42c4f778f755c1a9e82f168a8925acd8..a64f6a1d2fa169fbd35ca4eeae03d2be4b61bef7 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -1850,11 +1850,11 @@ class LCallJSFunction V8_FINAL : public LTemplateInstruction<1, 1, 0> {
 
 class LCallWithDescriptor V8_FINAL : public LTemplateResultInstruction<1> {
  public:
-  LCallWithDescriptor(const CallInterfaceDescriptor* descriptor,
+  LCallWithDescriptor(const InterfaceDescriptor* descriptor,
                       const ZoneList<LOperand*>& operands,
                       Zone* zone)
-    : inputs_(descriptor->environment_length() + 1, zone) {
-    ASSERT(descriptor->environment_length() + 1 == operands.length());
+    : inputs_(descriptor->GetRegisterParameterCount() + 1, zone) {
+    ASSERT(descriptor->GetRegisterParameterCount() + 1 == operands.length());
     inputs_.AddAll(operands, zone);
   }