[analyzer] CheckerContext::getPredecessor() cleanup

Remove unnecessary calls to CheckerContext::getPredecessor() + Comments.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@143513 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp b/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
index 8f9f7d5..4969546 100644
--- a/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
@@ -2606,13 +2606,12 @@
 void RetainCountChecker::checkPostObjCMessage(const ObjCMessage &Msg, 
                                               CheckerContext &C) const {
   const ProgramState *state = C.getState();
-  ExplodedNode *Pred = C.getPredecessor();
 
   RetainSummaryManager &Summaries = getSummaryManager(C);
 
   const RetainSummary *Summ;
   if (Msg.isInstanceMessage()) {
-    const LocationContext *LC = Pred->getLocationContext();
+    const LocationContext *LC = C.getLocationContext();
     Summ = Summaries.getInstanceMethodSummary(Msg, state, LC);
   } else {
     Summ = Summaries.getClassMethodSummary(Msg);