Don't NFC normalize filenames in form data

Don't NFC normalize filenames in form data

When building the payload for POST data with files, Blink was
normalizing strings. Similar to crbug.com/427183, we're calling
normalizeAndEncode() when encode() is more appropriate, and matches
the behavior in other browsers.

BUG=341019
R=tkent@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201590

[jsbell, 2015-09-02 00:00:12]

tkent@ - please take a look?

Something in my filesystem/console/etc seems to enjoy normalizing filenames
locally before I can get them into Chrome, so I'm not able to repro with actual
files and "Copy as cURL", although the test definitely reproduces the problem
and fails w/o the fix.

[tkent, 2015-09-02 00:01:53]

lgtm

[jsbell, 2015-09-02 00:10:53]

The CQ bit was checked by jsbell@chromium.org

[commit-bot: I haz the power, 2015-09-02 00:10:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1306073004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1306073004/1

[commit-bot: I haz the power, 2015-09-02 01:00:53]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201590