Move reusable handles from isolate to thread.

runtime/vm/native_entry.cc

Index: runtime/vm/native_entry.cc
diff --git a/runtime/vm/native_entry.cc b/runtime/vm/native_entry.cc
index 29cb8d7145b9d8f89ca9eb40747cdc8071bbd104..84dd6e9f34d0938581b5ef0414c85e4f892792f5 100644
--- a/runtime/vm/native_entry.cc
+++ b/runtime/vm/native_entry.cc
@@ -56,14 +56,14 @@ const uint8_t* NativeEntry::ResolveSymbolInLibrary(const Library& library,
 
 
 const uint8_t* NativeEntry::ResolveSymbol(uword pc) {
-  Isolate* isolate = Isolate::Current();
-  REUSABLE_GROWABLE_OBJECT_ARRAY_HANDLESCOPE(isolate);
+  Thread* thread = Thread::Current();
+  REUSABLE_GROWABLE_OBJECT_ARRAY_HANDLESCOPE(thread);
   GrowableObjectArray& libs = reused_growable_object_array_handle.Handle();
-  libs ^= isolate->object_store()->libraries();
+  libs ^= thread->isolate()->object_store()->libraries();
   ASSERT(!libs.IsNull());
   intptr_t num_libs = libs.Length();
   for (intptr_t i = 0; i < num_libs; i++) {
-    REUSABLE_LIBRARY_HANDLESCOPE(isolate);
+    REUSABLE_LIBRARY_HANDLESCOPE(thread);
     Library& lib = reused_library_handle.Handle();
     lib ^= libs.At(i);
     ASSERT(!lib.IsNull());