Reland "Add UnencodableHandling::kNoUnencodables"

This reverts commit 303d77a1e1d389f42b02fc04541e83e7ae9b12cf.

Reason for revert: Did not fix the issue

Original change's description:
> Revert "Add UnencodableHandling::kNoUnencodables"
> 
> This reverts commit b4edab2474e7269cbeeb33b0f8e6e82920b179a3.
> 
> Reason for revert: 
> 
> Webkit tests on Android nx4 are failing since:
> https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Android%20%28Nexus4%29/82322
> 
> speculative revert (sorry) since this is the only CL in the blame list realted to text encoding and the error says:
> 
> "
> UnicodeDecodeError raised: 'ascii' codec can't decode byte 0xe2 in position 146896: ordinal not in range(128)
> ...
> "
> 
> Original change's description:
> > Add UnencodableHandling::kNoUnencodables
> > 
> > The are no unencodable characters in UTF-8, however previously callers
> > to blink::TextCoder::Encode had to pass a dummy UnencodableHandling
> > argument. Add a kNoUnencodables value to the UnencodableHandling which is
> > an explicit no-op. Also add DCHECKs that is is only used for UTF-8 or
> > UTF-16.
> > 
> > Convert callers to use kNoUnencodables where the encoding is statically
> > known to be UTF-8.
> > 
> > It's still valid to use other values for the UnencodableHandling
> > argument with UTF-8 or UTF-16; kNoUnencodables simply documents that it
> > makes no difference.
> > 
> > Change-Id: I5eebe4c76ae4006ee91f3884f94ec3b5e410685b
> > Reviewed-on: https://chromium-review.googlesource.com/1206055
> > Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
> > Reviewed-by: Kentaro Hara <haraken@chromium.org>
> > Reviewed-by: Joshua Bell <jsbell@chromium.org>
> > Commit-Queue: Adam Rice <ricea@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#589451}
> 
> TBR=jsbell@chromium.org,ricea@chromium.org,yhirano@chromium.org,haraken@chromium.org
> 
> Change-Id: Iaddd13dc7e2fe9473528710dcdaf080f50d01ecc
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://chromium-review.googlesource.com/1213085
> Reviewed-by: Markus Heintz <markusheintz@chromium.org>
> Commit-Queue: Markus Heintz <markusheintz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#589501}

TBR=jsbell@chromium.org,ricea@chromium.org,markusheintz@chromium.org,yhirano@chromium.org,haraken@chromium.org

Change-Id: I51221bfefd2e5d9505b05615ab38e5b1602e2fdf
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/1213172
Reviewed-by: Markus Heintz <markusheintz@chromium.org>
Commit-Queue: Markus Heintz <markusheintz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589510}
12 files changed