Use the right TextRun length when checking for surrogate pairs

Use the right TextRun length when checking for surrogate pairs

The isValidSurrogatePair helper in LayoutSVGInlineText.cpp operates on a
TextRun and an index, and checks if the character at the index is part
of a valid surrogate pair.
To check the trailing character, the next index is checked against the
length of the TextRun (to see if the character exists).
The TextRun used is a "sub run" of the entire text node, which means
that the operator[] implementation expects accesses to be within the sub
run rather than the "full run".
Since this function is always used for runs that are sub runs, it should
use TextRun::length() rather than TextRun::charactersLength() to stay
consistent with the iteration and the code using it.

BUG=610641
Review-Url: https://codereview.chromium.org/1961953004
Cr-Commit-Position: refs/heads/master@{#392880}
(cherry picked from commit 7dabd875312333379d052e609cc9aad621de1754)

Committed: https://chromium.googlesource.com/chromium/src/+/80b28a30853ef60bf7c8c4c2c2b47e08569252e3

[fs, 2016-05-24 10:37:53]

Description was changed from

==========
Use the right TextRun length when checking for surrogate pairs

The isValidSurrogatePair helper in LayoutSVGInlineText.cpp operates on a
TextRun and an index, and checks if the character at the index is part
of a valid surrogate pair.
To check the trailing character, the next index is checked against the
length of the TextRun (to see if the character exists).
The TextRun used is a "sub run" of the entire text node, which means
that the operator[] implementation expects accesses to be within the sub
run rather than the "full run".
Since this function is always used for runs that are sub runs, it should
use TextRun::length() rather than TextRun::charactersLength() to stay
consistent with the iteration and the code using it.

BUG=610641

Review-Url: https://codereview.chromium.org/1961953004
Cr-Commit-Position: refs/heads/master@{#392880}
(cherry picked from commit 7dabd875312333379d052e609cc9aad621de1754)
==========

to

==========
Use the right TextRun length when checking for surrogate pairs

The isValidSurrogatePair helper in LayoutSVGInlineText.cpp operates on a
TextRun and an index, and checks if the character at the index is part
of a valid surrogate pair.
To check the trailing character, the next index is checked against the
length of the TextRun (to see if the character exists).
The TextRun used is a "sub run" of the entire text node, which means
that the operator[] implementation expects accesses to be within the sub
run rather than the "full run".
Since this function is always used for runs that are sub runs, it should
use TextRun::length() rather than TextRun::charactersLength() to stay
consistent with the iteration and the code using it.

BUG=610641

Review-Url: https://codereview.chromium.org/1961953004
Cr-Commit-Position: refs/heads/master@{#392880}
(cherry picked from commit 7dabd875312333379d052e609cc9aad621de1754)

Committed:
https://chromium.googlesource.com/chromium/src/+/80b28a30853ef60bf7c8c4c2c2b4...
==========

[fs, 2016-05-24 10:37:55]

Committed patchset #1 (id:1) manually as
80b28a30853ef60bf7c8c4c2c2b47e08569252e3 (tree was closed).