Tighten up assertions checking GC-safety of stub calls.

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index 9813657e1a80f05c3b947268f52fa9ec82be55f8..9a0ba101ac5ade5e1c05fa7b26f08dba20f48e46 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -773,6 +773,9 @@ void BinaryOpStub::GenerateTypeTransition(MacroAssembler* masm) {
 
 
 void BinaryOpStub::Generate(MacroAssembler* masm) {
+  // Explicitly allow generation of nested stubs. It is safe here.
+  AllowStubCallsScope allow_stub_calls(masm, true);
+
   switch (operands_type_) {
     case BinaryOpIC::UNINITIALIZED:
       GenerateTypeTransition(masm);
@@ -3349,7 +3352,7 @@ bool CEntryStub::NeedsImmovableCode() {
 }
 
 
-bool CEntryStub::CompilingCallsToThisStubIsGCSafe() {
+bool CEntryStub::IsPregenerated() {
   return result_size_ == 1;
 }
 
@@ -5578,7 +5581,7 @@ struct AheadOfTimeWriteBarrierStubList kAheadOfTime[] = {
 };
 
 
-bool RecordWriteStub::CompilingCallsToThisStubIsGCSafe() {
+bool RecordWriteStub::IsPregenerated() {
   for (AheadOfTimeWriteBarrierStubList* entry = kAheadOfTime;
        !entry->object.is(no_reg);
        entry++) {