ART: Add dex::StringIndex

Add abstraction for uint32_t string index.

Test: m test-art-host
Change-Id: I917c2881702fe3df112c713f06980f2278ced7ed
diff --git a/runtime/interpreter/interpreter_switch_impl.cc b/runtime/interpreter/interpreter_switch_impl.cc
index 22c0fe0..52eacd5 100644
--- a/runtime/interpreter/interpreter_switch_impl.cc
+++ b/runtime/interpreter/interpreter_switch_impl.cc
@@ -373,7 +373,9 @@
         break;
       case Instruction::CONST_STRING: {
         PREAMBLE();
-        ObjPtr<mirror::String> s = ResolveString(self, shadow_frame,  inst->VRegB_21c());
+        ObjPtr<mirror::String> s = ResolveString(self,
+                                                 shadow_frame,
+                                                 dex::StringIndex(inst->VRegB_21c()));
         if (UNLIKELY(s == nullptr)) {
           HANDLE_PENDING_EXCEPTION();
         } else {
@@ -384,7 +386,9 @@
       }
       case Instruction::CONST_STRING_JUMBO: {
         PREAMBLE();
-        ObjPtr<mirror::String> s = ResolveString(self, shadow_frame,  inst->VRegB_31c());
+        ObjPtr<mirror::String> s = ResolveString(self,
+                                                 shadow_frame,
+                                                 dex::StringIndex(inst->VRegB_31c()));
         if (UNLIKELY(s == nullptr)) {
           HANDLE_PENDING_EXCEPTION();
         } else {