ART: Add dex::StringIndex

Add abstraction for uint32_t string index.

Test: m test-art-host
Change-Id: I917c2881702fe3df112c713f06980f2278ced7ed
diff --git a/oatdump/oatdump.cc b/oatdump/oatdump.cc
index 3ad0f1e..a1984a7 100644
--- a/oatdump/oatdump.cc
+++ b/oatdump/oatdump.cc
@@ -703,13 +703,13 @@
         const Instruction* inst = Instruction::At(code_ptr);
         switch (inst->Opcode()) {
           case Instruction::CONST_STRING: {
-            const uint32_t string_index = inst->VRegB_21c();
+            const dex::StringIndex string_index(inst->VRegB_21c());
             unique_string_ids_from_code_.insert(StringReference(&dex_file, string_index));
             ++num_string_ids_from_code_;
             break;
           }
           case Instruction::CONST_STRING_JUMBO: {
-            const uint32_t string_index = inst->VRegB_31c();
+            const dex::StringIndex string_index(inst->VRegB_31c());
             unique_string_ids_from_code_.insert(StringReference(&dex_file, string_index));
             ++num_string_ids_from_code_;
             break;