Use class def index from java.lang.Class.

Bug: 10244719
This removes the computation of the dex file index, when necessary this is
computed by searching the dex file. Its only necessary in
dalvik.system.DexFile.defineClassNative and DexFile::FindInClassPath, the
latter not showing up significantly in profiling with this change.

(cherry-picked from 8b2c0b9abc3f520495f4387ea040132ba85cae69)
Change-Id: I20c73a3b17d86286428ab0fd21bc13f51f36c85c
diff --git a/compiler/llvm/compiler_llvm.cc b/compiler/llvm/compiler_llvm.cc
index fd440d5..a917cdc 100644
--- a/compiler/llvm/compiler_llvm.cc
+++ b/compiler/llvm/compiler_llvm.cc
@@ -39,7 +39,7 @@
                       const CompilerBackend compilerBackend,
                       const DexFile::CodeItem* code_item,
                       uint32_t access_flags, InvokeType invoke_type,
-                      uint32_t class_def_idx, uint32_t method_idx, jobject class_loader,
+                      uint16_t class_def_idx, uint32_t method_idx, jobject class_loader,
                       const DexFile& dex_file,
                       llvm::LlvmCompilationUnit* llvm_info);
 }
@@ -202,7 +202,7 @@
                                                  const art::DexFile::CodeItem* code_item,
                                                  uint32_t access_flags,
                                                  art::InvokeType invoke_type,
-                                                 uint32_t class_def_idx,
+                                                 uint16_t class_def_idx,
                                                  uint32_t method_idx,
                                                  jobject class_loader,
                                                  const art::DexFile& dex_file) {