Rename TemplateArgument::getTypeForDecl to getParamTypeForDecl for clarity

Code review feedback from Richard Smith on r219900.

llvm-svn: 220060
diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index fe5a502..5965ef0 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -3403,7 +3403,7 @@
     // and pointer-to-function expressions are represented as a declaration not
     // an expression. We compensate for it here to produce the correct mangling.
     ValueDecl *D = A.getAsDecl();
-    bool compensateMangling = !A.getTypeForDecl()->isReferenceType();
+    bool compensateMangling = !A.getParamTypeForDecl()->isReferenceType();
     if (compensateMangling) {
       Out << 'X';
       mangleOperatorName(OO_Amp, 1);