Fix StoreIsUninitialized, and add Soft Deopt if keyed store is uninitialized.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 096c4e3356a9548c99bac1bed77a9460cbdbd110..79ce3a522101785a90dccbdf674310c573ca9aa5 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -5996,8 +5996,14 @@ HValue* HOptimizedGraphBuilder::HandleKeyedElementAccess(
         expr->GetStoreMode(), has_side_effects);
   } else {
     if (is_store) {
+      if (expr->IsAssignment() && expr->AsAssignment()->IsUninitialized()) {
+        AddSoftDeoptimize();
+      }
       instr = BuildStoreKeyedGeneric(obj, key, val);
     } else {
+      if (expr->AsProperty()->IsUninitialized()) {
+        AddSoftDeoptimize();
+      }
       instr = BuildLoadKeyedGeneric(obj, key);
     }
     AddInstruction(instr);