Revert "Annotate used fields."

This reverts commit 7f6cf56942c8469958b273ea968db253051c5b05.

Change-Id: Ic389a194c3404ecb5bb563a405bf4a0d6336ea0d
diff --git a/compiler/dex/mir_graph.cc b/compiler/dex/mir_graph.cc
index 39f2d0e..e4550d1 100644
--- a/compiler/dex/mir_graph.cc
+++ b/compiler/dex/mir_graph.cc
@@ -86,9 +86,7 @@
       forward_branches_(0),
       compiler_temps_(arena, 6, kGrowableArrayMisc),
       num_non_special_compiler_temps_(0),
-      max_available_non_special_compiler_temps_(0),
-      ifield_annotations_(arena, 0u),
-      sfield_annotations_(arena, 0u) {
+      max_available_non_special_compiler_temps_(0) {
   try_block_addr_ = new (arena_) ArenaBitVector(arena_, 0, true /* expandable */);
   max_available_special_compiler_temps_ = std::abs(static_cast<int>(kVRegNonSpecialTempBaseReg))
       - std::abs(static_cast<int>(kVRegTempBaseReg));