Allocation site pretenuring for StringAdd on all platforms.

BUG=
R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/147763005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18882 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/lithium-codegen-arm.cc

@@ -4505,7 +4505,7 @@ void LCodeGen::DoStringAdd(LStringAdd* instr) {
   ASSERT(ToRegister(instr->left()).is(r1));
   ASSERT(ToRegister(instr->right()).is(r0));
   StringAddStub stub(instr->hydrogen()->flags(),
-                     isolate()->heap()->GetPretenureMode());
+                     instr->hydrogen()->pretenure_flag());
   CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
 }
 

src/mips/lithium-codegen-mips.cc

@@ -4440,7 +4440,7 @@ void LCodeGen::DoStringAdd(LStringAdd* instr) {
   ASSERT(ToRegister(instr->left()).is(a1));
   ASSERT(ToRegister(instr->right()).is(a0));
   StringAddStub stub(instr->hydrogen()->flags(),
-                     isolate()->heap()->GetPretenureMode());
+                     instr->hydrogen()->pretenure_flag());
   CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
 }
 

src/x64/lithium-codegen-x64.cc

@@ -4385,7 +4385,7 @@ void LCodeGen::DoStringAdd(LStringAdd* instr) {
   ASSERT(ToRegister(instr->left()).is(rdx));
   ASSERT(ToRegister(instr->right()).is(rax));
   StringAddStub stub(instr->hydrogen()->flags(),
-                     isolate()->heap()->GetPretenureMode());
+                     instr->hydrogen()->pretenure_flag());
   CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
 }