ART: Add dex::StringIndex

Add abstraction for uint32_t string index.

Test: m test-art-host
Change-Id: I917c2881702fe3df112c713f06980f2278ced7ed
diff --git a/runtime/interpreter/mterp/mterp.cc b/runtime/interpreter/mterp/mterp.cc
index fbfed40..c8c1563 100644
--- a/runtime/interpreter/mterp/mterp.cc
+++ b/runtime/interpreter/mterp/mterp.cc
@@ -291,7 +291,7 @@
                                    ShadowFrame* shadow_frame,
                                    Thread* self)
     REQUIRES_SHARED(Locks::mutator_lock_) {
-  ObjPtr<mirror::String> s = ResolveString(self, *shadow_frame, index);
+  ObjPtr<mirror::String> s = ResolveString(self, *shadow_frame, dex::StringIndex(index));
   if (UNLIKELY(s == nullptr)) {
     return true;
   }