Fix printing issue of list item with blank first line

Fix printing issue of list item with blank first line

The problem was that LayoutObject::addElementVisualOverflowRects()
doesn't cover list markers. Filed crbug.com/614781 for this.

Let BlockPainter unite its visual overflow and the result of
addElementVisualOverflowRects() to ensure whole visual overflow
coverage.

BUG=614262
TEST=printing/list-item-with-empty-first-line.html

Review-Url: https://codereview.chromium.org/2011863005
Cr-Commit-Position: refs/heads/master@{#396046}

Committed: https://chromium.googlesource.com/chromium/src/+/343998e6bc865e694516e2c340d47d1d171345f7

[Xianzhu, 2016-05-27 19:04:03]

Description was changed from

==========
Fix printing issue of list item with blank first line

The problem was that LayoutObject::addElementVisualOverflowRects()
doesn't cover list markers. Filed crbug.com/614781 for this.

Let BlockPainter unite its visual overflow and the result of
addElementVisualOverflowRects() to ensure whole visual overflow
coverage.

BUG=614262
TEST=printing/list-item-with-empty-first-line.html

Review-Url: https://codereview.chromium.org/2011863005
Cr-Commit-Position: refs/heads/master@{#396046}
==========

to

==========
Fix printing issue of list item with blank first line

The problem was that LayoutObject::addElementVisualOverflowRects()
doesn't cover list markers. Filed crbug.com/614781 for this.

Let BlockPainter unite its visual overflow and the result of
addElementVisualOverflowRects() to ensure whole visual overflow
coverage.

BUG=614262
TEST=printing/list-item-with-empty-first-line.html

Review-Url: https://codereview.chromium.org/2011863005
Cr-Commit-Position: refs/heads/master@{#396046}

Committed:
https://chromium.googlesource.com/chromium/src/+/343998e6bc865e694516e2c340d4...
==========

[Xianzhu, 2016-05-27 19:04:05]

Committed patchset #1 (id:1) manually as
343998e6bc865e694516e2c340d47d1d171345f7.