Rename WeakVH to WeakTrackingVH; NFC

This relands r301424.

llvm-svn: 301812
diff --git a/llvm/lib/Analysis/CallGraphSCCPass.cpp b/llvm/lib/Analysis/CallGraphSCCPass.cpp
index ea70f57..8058e5b 100644
--- a/llvm/lib/Analysis/CallGraphSCCPass.cpp
+++ b/llvm/lib/Analysis/CallGraphSCCPass.cpp
@@ -204,7 +204,7 @@
     // Get the set of call sites currently in the function.
     for (CallGraphNode::iterator I = CGN->begin(), E = CGN->end(); I != E; ) {
       // If this call site is null, then the function pass deleted the call
-      // entirely and the WeakVH nulled it out.  
+      // entirely and the WeakTrackingVH nulled it out.
       if (!I->first ||
           // If we've already seen this call site, then the FunctionPass RAUW'd
           // one call with another, which resulted in two "uses" in the edge
@@ -347,7 +347,8 @@
       DevirtualizedCall = true;
     
     // After scanning this function, if we still have entries in callsites, then
-    // they are dangling pointers.  WeakVH should save us for this, so abort if
+    // they are dangling pointers.  WeakTrackingVH should save us for this, so
+    // abort if
     // this happens.
     assert(CallSites.empty() && "Dangling pointers found in call sites map");