Revert "Revert "Revert "Revert "Add implicit null and stack checks for x86""""

This reverts commit 0025a86411145eb7cd4971f9234fc21c7b4aced1.

Bug: 16256184
Change-Id: Ie0760a0c293aa3b62e2885398a8c512b7a946a73
diff --git a/runtime/runtime.h b/runtime/runtime.h
index fccccbd..284e4ff 100644
--- a/runtime/runtime.h
+++ b/runtime/runtime.h
@@ -589,6 +589,11 @@
   // Specifies target SDK version to allow workarounds for certain API levels.
   int32_t target_sdk_version_;
 
+  // Implicit checks flags.
+  bool implicit_null_checks_;       // NullPointer checks are implicit.
+  bool implicit_so_checks_;         // StackOverflow checks are implicit.
+  bool implicit_suspend_checks_;    // Thread suspension checks are implicit.
+
   DISALLOW_COPY_AND_ASSIGN(Runtime);
 };