Enable Oilpan by default for core/fileapi

This CL enables Oilpan by default for File, Blob, FileList, FileReader and FileReaderSync. These objects are not performance-sensitive, so there would be little concern about enabling Oilpan for these objects.

I'm planning to enable Oilpan for FileError in the next patch.

BUG=340522

Review URL: https://codereview.chromium.org/588073003

git-svn-id: svn://svn.chromium.org/blink/trunk@183030 bbb929c8-8fbe-4397-9dbb-9b2b20218538