ART: Clean up field initialization

Add explicit field initialization to default value where necessary.
Also clean up interpreter intrinsics header.

Test: m
Change-Id: I7a850ac30dcccfb523a5569fb8400b9ac892c8e5
diff --git a/compiler/optimizing/cha_guard_optimization.cc b/compiler/optimizing/cha_guard_optimization.cc
index fe42301..4f160ae 100644
--- a/compiler/optimizing/cha_guard_optimization.cc
+++ b/compiler/optimizing/cha_guard_optimization.cc
@@ -36,7 +36,8 @@
       : HGraphVisitor(graph),
         block_has_cha_guard_(GetGraph()->GetBlocks().size(),
                              0,
-                             graph->GetArena()->Adapter(kArenaAllocCHA)) {
+                             graph->GetArena()->Adapter(kArenaAllocCHA)),
+        instruction_iterator_(nullptr) {
     number_of_guards_to_visit_ = GetGraph()->GetNumberOfCHAGuards();
     DCHECK_NE(number_of_guards_to_visit_, 0u);
     // Will recount number of guards during guard optimization.