Bug fix: Make RecursiveASTVisitor<T>::TraverseLambdaExpr call
WalkUpFromLambdaExpr, so that the Visit* functions are called
on that AST node.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@185277 91177308-0d34-0410-b5e6-96231b3b80d8