Do not crash when measuring empty SVG text nodes

Do not crash when measuring empty SVG text nodes

A regression was introduced by [1] where the loop in
SVGTextMetricsBuilder::measureTextLayoutObject would no longer check
if there was any text before attempting to measure the text. This patch
adds the trivial empty text check and adds a new test for this edgecase.

[1] https://chromium.googlesource.com/chromium/src/+/304ec1544273ed8d62c693da6dd2c63727805cdd

BUG=596148, 589525
Committed: https://crrev.com/8e375826a04e52a50c4656f64eaa29c7fb05927c
Cr-Commit-Position: refs/heads/master@{#382170}

[pdr., 2016-03-19 00:05:07]

pdr@chromium.org changed reviewers:
+ chrishtr@chromium.org, fs@opera.com

[pdr., 2016-03-19 00:05:21]

The CQ bit was checked by pdr@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-03-19 00:05:54]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1806263005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1806263005/1

[chrishtr, 2016-03-19 00:12:00]

lgtm

[fs, 2016-03-19 00:13:33]

lgtm

[commit-bot: I haz the power, 2016-03-19 02:23:02]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-03-19 02:23:03]

Dry run: This issue passed the CQ dry run.

[pdr., 2016-03-19 02:24:25]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2016-03-19 02:24:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1806263005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1806263005/1

[commit-bot: I haz the power, 2016-03-19 02:30:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-03-19 02:31:54]

Description was changed from

==========
Do not crash when measuring empty SVG text nodes

A regression was introduced by [1] where the loop in
SVGTextMetricsBuilder::measureTextLayoutObject would no longer check
if there was any text before attempting to measure the text. This patch
adds the trivial empty text check and adds a new test for this edgecase.

[1]
https://chromium.googlesource.com/chromium/src/+/304ec1544273ed8d62c693da6dd2...

BUG=596148,589525
==========

to

==========
Do not crash when measuring empty SVG text nodes

A regression was introduced by [1] where the loop in
SVGTextMetricsBuilder::measureTextLayoutObject would no longer check
if there was any text before attempting to measure the text. This patch
adds the trivial empty text check and adds a new test for this edgecase.

[1]
https://chromium.googlesource.com/chromium/src/+/304ec1544273ed8d62c693da6dd2...

BUG=596148,589525

Committed: https://crrev.com/8e375826a04e52a50c4656f64eaa29c7fb05927c
Cr-Commit-Position: refs/heads/master@{#382170}
==========

[commit-bot: I haz the power, 2016-03-19 02:31:55]

Patchset 1 (id:??) landed as
https://crrev.com/8e375826a04e52a50c4656f64eaa29c7fb05927c
Cr-Commit-Position: refs/heads/master@{#382170}