Add a missing check for exceptions thrown in methods implemented in private scripts

method.cpp misses a check for a returned value of a method implemented in a private script.
This CL adds the check. Other places already have the check.

(This call path is not yet used in production.)

BUG=341031

Review URL: https://codereview.chromium.org/462623002

git-svn-id: svn://svn.chromium.org/blink/trunk@179943 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove custom getters for File.lastModified{Date}

No particular need for these to be custom, so turned into File accessors
instead.

Also drop a runtime feature check for FileConstructor; it is now stable.

R=haraken
BUG=

Review URL: https://codereview.chromium.org/458953002

git-svn-id: svn://svn.chromium.org/blink/trunk@179944 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: DataGrid: simplify CSS.

BUG=
NOTRY=true

Review URL: https://codereview.chromium.org/458903003

git-svn-id: svn://svn.chromium.org/blink/trunk@179945 bbb929c8-8fbe-4397-9dbb-9b2b20218538