remove most uses of Isolate::Current in arch specific files

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index 7133f3b41233d7695e5b23bf92b328dbc4f0fca8..88b216b29c32caa78cd7386b93b899067ec8d544 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -4430,8 +4430,8 @@ bool CEntryStub::NeedsImmovableCode() {
 }
 
 
-bool CEntryStub::IsPregenerated() {
-  return (!save_doubles_ || Isolate::Current()->fp_stubs_generated()) &&
+bool CEntryStub::IsPregenerated(Isolate* isolate) {
+  return (!save_doubles_ || isolate->fp_stubs_generated()) &&
           result_size_ == 1;
 }
 
@@ -6847,7 +6847,7 @@ static const AheadOfTimeWriteBarrierStubList kAheadOfTime[] = {
 
 #undef REG
 
-bool RecordWriteStub::IsPregenerated() {
+bool RecordWriteStub::IsPregenerated(Isolate* isolate) {
   for (const AheadOfTimeWriteBarrierStubList* entry = kAheadOfTime;
        !entry->object.is(no_reg);
        entry++) {