Tighten up assertions checking GC-safety of stub calls.

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index d586b0a4d4a73655c14319e6941155b28c2db8d5..eb4b9f1f23718343029c3b1735e88f21edb602ae 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -508,7 +508,7 @@ MaybeObject* MacroAssembler::TryCallStub(CodeStub* stub) {
 
 
 void MacroAssembler::TailCallStub(CodeStub* stub) {
-  ASSERT(stub->CompilingCallsToThisStubIsGCSafe() || allow_stub_calls_);
+  ASSERT(allow_stub_calls_ || stub->CompilingCallsToThisStubIsGCSafe());
   Jump(stub->GetCode(), RelocInfo::CODE_TARGET);
 }
 
@@ -531,7 +531,7 @@ void MacroAssembler::StubReturn(int argc) {
 
 bool MacroAssembler::AllowThisStubCall(CodeStub* stub) {
   if (!has_frame_ && stub->SometimesSetsUpAFrame()) return false;
-  return stub->CompilingCallsToThisStubIsGCSafe() || allow_stub_calls_;
+  return allow_stub_calls_ || stub->CompilingCallsToThisStubIsGCSafe();
 }