Remove unused method in DEX-to-DEX.

Change-Id: Ice5f91b45a0ad85576475a613193f143fd76ad9f
diff --git a/compiler/dex/dex_to_dex_compiler.cc b/compiler/dex/dex_to_dex_compiler.cc
index abafbc5..3368132 100644
--- a/compiler/dex/dex_to_dex_compiler.cc
+++ b/compiler/dex/dex_to_dex_compiler.cc
@@ -52,12 +52,6 @@
     return *unit_.GetDexFile();
   }
 
-  // TODO: since the whole compilation pipeline uses a "const DexFile", we need
-  // to "unconst" here. The DEX-to-DEX compiler should work on a non-const DexFile.
-  DexFile& GetModifiableDexFile() {
-    return *const_cast<DexFile*>(unit_.GetDexFile());
-  }
-
   bool PerformOptimizations() const {
     return dex_to_dex_compilation_level_ >= kOptimize;
   }