The File API reader validates that the "expected" modification time -
e.g. taken when a user selects a file via <input type=file> matches
the "actual" modification time when trying to read. Certain file
timestamps (on Windows/NTFS at least) are high enough precision
(tenths of microseconds) that an int64->double->int64 round trip
through Blink loses bits. Files with these timestamps can't be read!
Sample timestamp: 2011-01-01T01:23:45.999999Z (that's a lot of 9s)
Make the comparison with an epsilon of 10us.
BUG=525088
R=michaeln@chromium.org
Review URL: https://codereview.chromium.org/1308773006
Cr-Commit-Position: refs/heads/master@{#346802}
1d45da203a