[strong] Implement strong mode semantics for the count operation.

src/ia32/full-codegen-ia32.cc

Index: src/ia32/full-codegen-ia32.cc
diff --git a/src/ia32/full-codegen-ia32.cc b/src/ia32/full-codegen-ia32.cc
index 04d48bdfdfb581c57096e8502ad50ee67f8531c2..2f1fbdb182822d6ecdfd6f8a7724ea116ffce995 100644
--- a/src/ia32/full-codegen-ia32.cc
+++ b/src/ia32/full-codegen-ia32.cc
@@ -4957,9 +4957,11 @@ void FullCodeGenerator::VisitCountOperation(CountOperation* expr) {
     __ jmp(&stub_call, Label::kNear);
     __ bind(&slow);
   }
-  ToNumberStub convert_stub(isolate());
-  __ CallStub(&convert_stub);
-  PrepareForBailoutForId(expr->ToNumberId(), TOS_REG);
+  if (!is_strong(language_mode())) {
+    ToNumberStub convert_stub(isolate());
+    __ CallStub(&convert_stub);
+    PrepareForBailoutForId(expr->ToNumberId(), TOS_REG);
+  }
 
   // Save result for postfix expressions.
   if (expr->is_postfix()) {
@@ -5000,6 +5002,9 @@ void FullCodeGenerator::VisitCountOperation(CountOperation* expr) {
   patch_site.EmitPatchInfo();
   __ bind(&done);
 
+  if (is_strong(language_mode())) {
+    PrepareForBailoutForId(expr->ToNumberId(), TOS_REG);
+  }
   // Store the value returned in eax.
   switch (assign_type) {
     case VARIABLE: