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

src/ia32/debug-ia32.cc

Index: src/ia32/debug-ia32.cc
diff --git a/src/ia32/debug-ia32.cc b/src/ia32/debug-ia32.cc
index fd703dcc0c7fb145e41f8cb97e0bbdc6a1fea124..76a7003bfe015ac60e89ab1d432bd91989a3c0d9 100644
--- a/src/ia32/debug-ia32.cc
+++ b/src/ia32/debug-ia32.cc
@@ -49,8 +49,8 @@ bool BreakLocationIterator::IsDebugBreakAtReturn() {
 void BreakLocationIterator::SetDebugBreakAtReturn() {
   ASSERT(Assembler::kJSReturnSequenceLength >=
          Assembler::kCallInstructionLength);
-  Isolate* isolate = Isolate::Current();
-  rinfo()->PatchCodeWithCall(isolate->debug()->debug_break_return()->entry(),
+  rinfo()->PatchCodeWithCall(
+      debug_info_->GetIsolate()->debug()->debug_break_return()->entry(),
       Assembler::kJSReturnSequenceLength - Assembler::kCallInstructionLength);
 }
 
@@ -79,7 +79,7 @@ bool BreakLocationIterator::IsDebugBreakAtSlot() {
 
 void BreakLocationIterator::SetDebugBreakAtSlot() {
   ASSERT(IsDebugBreakSlot());
-  Isolate* isolate = Isolate::Current();
+  Isolate* isolate = debug_info_->GetIsolate();
   rinfo()->PatchCodeWithCall(
       isolate->debug()->debug_break_slot()->entry(),
       Assembler::kDebugBreakSlotLength - Assembler::kCallInstructionLength);