A few tweaks to MaterializeTemporaryExpr suggested by John.

llvm-svn: 133528
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index cdec049..7ca936a 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1313,8 +1313,7 @@
 }
 
 bool VarDecl::extendsLifetimeOfTemporary() const {
-  if (!getType()->isReferenceType())
-    return false;
+  assert(getType()->isReferenceType() &&"Non-references never extend lifetime");
   
   const Expr *E = getInit();
   if (!E)