[clang-format] Keep @message together in text protos

Summary:
In C++ code snippets of the form `@field` are common. This makes clang-format
keep them together in text protos, whereas before it would break them.

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D48543

llvm-svn: 335459
diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index 294c58d..1a5a6de 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -379,7 +379,8 @@
   if (Current.is(TT_ObjCMethodExpr) && !Previous.is(TT_SelectorName) &&
       State.Line->startsWith(TT_ObjCMethodSpecifier))
     return true;
-  if (Current.is(TT_SelectorName) && State.Stack.back().ObjCSelectorNameFound &&
+  if (Current.is(TT_SelectorName) && !Previous.is(tok::at) &&
+      State.Stack.back().ObjCSelectorNameFound &&
       State.Stack.back().BreakBeforeParameter)
     return true;