Do not pass DexFile to ClassLinker::Lookup/ResolveString().

The DexFile can be easily retrieved from the DexCache,
so reduce the number of arguments that need to be passed.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Change-Id: I8c4cec43b31b27de7e4e94374fdd69c6d6ca6c13
diff --git a/runtime/art_method.cc b/runtime/art_method.cc
index ebfa4fe..9005120 100644
--- a/runtime/art_method.cc
+++ b/runtime/art_method.cc
@@ -141,8 +141,7 @@
   auto* dex_file = dex_cache->GetDexFile();
   uint32_t dex_method_idx = GetDexMethodIndex();
   const DexFile::MethodId& method_id = dex_file->GetMethodId(dex_method_idx);
-  return Runtime::Current()->GetClassLinker()->ResolveString(*dex_file, method_id.name_idx_,
-                                                             dex_cache);
+  return Runtime::Current()->GetClassLinker()->ResolveString(method_id.name_idx_, dex_cache);
 }
 
 void ArtMethod::ThrowInvocationTimeError() {