Teach MemRegion::getBaseRegion() about ObjCIvarRegions.  We want to treat
them the same way as fields.  This fixes a regression in RegionStore::RemoveDeadbindings()
that emerged from going to the cluster-based analysis.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@100570 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Checker/MemRegion.cpp b/lib/Checker/MemRegion.cpp
index 9f12ab6..0571d81 100644
--- a/lib/Checker/MemRegion.cpp
+++ b/lib/Checker/MemRegion.cpp
@@ -647,13 +647,14 @@
 const MemRegion *MemRegion::getBaseRegion() const {
   const MemRegion *R = this;
   while (true) {
-    if (const ElementRegion *ER = dyn_cast<ElementRegion>(R)) {
-      R = ER->getSuperRegion();
-      continue;
-    }
-    if (const FieldRegion *FR = dyn_cast<FieldRegion>(R)) {
-      R = FR->getSuperRegion();
-      continue;
+    switch (R->getKind()) {
+      case MemRegion::ElementRegionKind:
+      case MemRegion::FieldRegionKind:
+      case MemRegion::ObjCIvarRegionKind:
+        R = cast<SubRegion>(R)->getSuperRegion();
+        continue;
+      default:
+        break;
     }
     break;
   }