[AST] Reduce Decl::getASTContext() calls.
 - This function is not at all free; pass it around along some hot paths instead
   of recomputing it deep inside various VarDecl methods.

llvm-svn: 152363
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 33656c9..062e4aa 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -6747,7 +6747,7 @@
         for (unsigned I = 0, N = Notes.size(); I != N; ++I)
           Diag(Notes[I].first, Notes[I].second);
       }
-    } else if (var->isUsableInConstantExpressions()) {
+    } else if (var->isUsableInConstantExpressions(Context)) {
       // Check whether the initializer of a const variable of integral or
       // enumeration type is an ICE now, since we can't tell whether it was
       // initialized by a constant expression if we check later.