Fix how YAML I/O detects flow sequences.  
Update test case to verify flow sequence is
written as a flow sequence.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171514 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/YAMLTraits.cpp b/lib/Support/YAMLTraits.cpp
index 8fcef40..ef3948d 100644
--- a/lib/Support/YAMLTraits.cpp
+++ b/lib/Support/YAMLTraits.cpp
@@ -411,8 +411,8 @@
 }
 
 unsigned Output::beginFlowSequence() {
-  this->newLineCheck();
   StateStack.push_back(inFlowSeq);
+  this->newLineCheck();
   ColumnAtFlowStart = Column;
   output("[ ");
   NeedFlowSequenceComma = false;