Follow-up to 'Default to "out" everywhere for the build directory'

I just noticed that there was a constant and a TODO note that
I meant to remove in a previous CL: https://crrev.com/c/546938/

Change-Id: Ib64f04407ecef335dbd1e4007ebc5a94971a5233
Reviewed-on: https://chromium-review.googlesource.com/553523
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Quinten Yearsley <qyearsley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#483283}

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/factory.py

@@ -163,10 +163,7 @@ def _check_configuration_and_target(host, options):
 
 def _read_configuration_from_gn(fs, options):
     """Returns the configuration to used based on args.gn, if possible."""
-
-    # TODO(qyearsley): Default to 'out' everywhere.
     build_directory = getattr(options, 'build_directory', 'out')
-
     target = options.target
     finder = PathFinder(fs)
     path = fs.join(finder.chromium_base(), build_directory, target, 'args.gn')

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py

@@ -45,8 +45,6 @@ class LinuxPort(base.Port):
     FALLBACK_PATHS = {}
     FALLBACK_PATHS['trusty'] = ['linux'] + win.WinPort.latest_platform_fallback_path()
 
-    DEFAULT_BUILD_DIRECTORIES = ('out',)
-
     BUILD_REQUIREMENTS_URL = 'https://chromium.googlesource.com/chromium/src/+/master/docs/linux_build_instructions.md'
 
     XVFB_START_TIMEOUT = 5.0  # Wait up to 5 seconds for Xvfb to start.