Report `only_throw_errors` on the expression not node.
Report `only_throw_errors` on the expression not node.

Reads a little better.

For example, given:

      throw adbResponse.message;

we know annotate only `adbResponse.message` (where previously we highlighted the entire line).

BUG=
R=brianwilkerson@google.com

Review URL: https://codereview.chromium.org//2191383002 .

alexeieleusis/dart-lang_linter,dart-lang/linter,dart-lang/linter,alexeieleusis/dart-lang_linter