Don't call FastNewFunctionContextStub if context is bigger than kMaxRegularHeapObjectSize.

src/full-codegen/x64/full-codegen-x64.cc

Index: src/full-codegen/x64/full-codegen-x64.cc
diff --git a/src/full-codegen/x64/full-codegen-x64.cc b/src/full-codegen/x64/full-codegen-x64.cc
index 05daaac458d4c37de185e1d8e1040b2cd880ea1c..c7dbe0f6bdb086b24184580cfadd4874c10e7d76 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -189,11 +189,16 @@ void FullCodeGenerator::Generate() {
       if (info->scope()->new_target_var() != nullptr) {
         __ Push(rdx);  // Preserve new target.
       }
-      FastNewFunctionContextStub stub(isolate());
-      __ Set(FastNewFunctionContextDescriptor::SlotsRegister(), slots);
-      __ CallStub(&stub);
-      // Result of FastNewFunctionContextStub is always in new space.
-      need_write_barrier = false;
+      if (slots <= FastNewFunctionContextStub::kMaximumSlots) {
+        FastNewFunctionContextStub stub(isolate());
+        __ Set(FastNewFunctionContextDescriptor::SlotsRegister(), slots);
+        __ CallStub(&stub);
+        // Result of FastNewFunctionContextStub is always in new space.
+        need_write_barrier = false;
+      } else {
+        __ Push(rdi);
+        __ CallRuntime(Runtime::kNewFunctionContext);
+      }
       if (info->scope()->new_target_var() != nullptr) {
         __ Pop(rdx);  // Restore new target.
       }