Improve comments.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@111897 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Checker/GRCXXExprEngine.cpp b/lib/Checker/GRCXXExprEngine.cpp
index 53c9ab6..a49989b 100644
--- a/lib/Checker/GRCXXExprEngine.cpp
+++ b/lib/Checker/GRCXXExprEngine.cpp
@@ -106,7 +106,8 @@
   for (ExplodedNodeSet::iterator NI = ArgsEvaluated.begin(),
                                  NE = ArgsEvaluated.end(); NI != NE; ++NI) {
     const GRState *state = GetState(*NI);
-    // Setup 'this' region.
+    // Setup 'this' region, so that the ctor is evaluated on the object pointed
+    // by 'Dest'.
     state = state->bindLoc(loc::MemRegionVal(ThisR), Dest);
     ExplodedNode *N = Builder->generateNode(Loc, state, Pred);
     if (N)