[Format/ObjC] Fix [foo bar]->baz formatting as lambda arrow

Summary:
Currently, `UnwrappedLineParser` thinks an arrow token after
an ObjC method expression is a C++ lambda arrow, so it formats:

```
[foo bar]->baz
```

as:

```
[foo bar] -> baz
```

Because `UnwrappedLineParser` runs before `TokenAnnotator`, it can't
know if the arrow token is after an ObjC method expression or not.

This diff makes `TokenAnnotator` remove the TT_LambdaArrow on
the arrow token if it follows an ObjC method expression.

Test Plan: New test added. Ran test with:
  % ninja FormatTests && ./tools/clang/unittests/Format/FormatTests
  Confirmed test failed before diff and passed after diff.

Reviewers: krasimir, djasper, sammccall

Reviewed By: sammccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D57923

llvm-svn: 353531