[turbofan] Check index type for potential element aliasing.

When deciding whether to nuke an element entry from the state table,
base the decision for the index only on the type information, and
don't even try to run it through the alias analyzer.

R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2301943002
Cr-Commit-Position: refs/heads/master@{#39116}

src/compiler/load-elimination.cc

@@ -216,7 +216,8 @@ LoadElimination::AbstractElements::Kill(Node* object, Node* index,
         DCHECK_NOT_NULL(element.index);
         DCHECK_NOT_NULL(element.value);
         if (!MayAlias(object, element.object) ||
-            !MayAlias(index, element.index)) {
+            !NodeProperties::GetType(index)->Maybe(
+                NodeProperties::GetType(element.index))) {
           that->elements_[that->next_index_++] = element;
         }
       }