Reapply "DWARF and unwind support for AOT assembly output."

runtime/vm/hash_map.h

Index: runtime/vm/hash_map.h
diff --git a/runtime/vm/hash_map.h b/runtime/vm/hash_map.h
index ff473013f4d643cd115d200dcf0a25fb716b1ce1..3bb99649bf0240f62da05fe71193650fc6115c76 100644
--- a/runtime/vm/hash_map.h
+++ b/runtime/vm/hash_map.h
@@ -39,6 +39,9 @@ class BaseDirectChainedHashMap : public B {
       typename KeyValueTrait::Key key) const;
 
   typename KeyValueTrait::Pair* Lookup(typename KeyValueTrait::Key key) const;
+  bool HasKey(typename KeyValueTrait::Key key) const {
+    return Lookup(key) != NULL;
+  }
 
   bool IsEmpty() const { return count_ == 0; }
 
@@ -378,6 +381,10 @@ class DirectChainedHashMap
   DirectChainedHashMap()
       : BaseDirectChainedHashMap<KeyValueTrait, ValueObject>(
             ASSERT_NOTNULL(Thread::Current()->zone())) {}
+
+  explicit DirectChainedHashMap(Zone* zone)
+      : BaseDirectChainedHashMap<KeyValueTrait, ValueObject>(
+            ASSERT_NOTNULL(zone)) {}
 };