Bug 97175 – Duplicate render objects should be removed when anonymous blocks are removed.

• Status: UNCONFIRMED
• Component: Layout and Rendering

[Takashi Sakamoto]

When some block element is inserted into inline element, anonymous render blocks will be created and 2 renderer of the inline element will be created under different anonymous render block. For example,

<span style="display: inline">
  <div></div>
</span>

Its render tree looks like:

RenderBlock (anonymous)
    RenderInline {SPAN}
RenderBlock (anonymous)
    RenderBlock {DIV}
RenderBlock (anonymous)
    RenderInline {SPAN}

When the <div> is removed, the RenderBlock(anonymous) will be removed in RenderBlock::removeChild. However, the code doesn't destroy duplicate RenderInline{SPAN}. So,

RenderInline {SPAN}
RenderInline {SPAN}

Two RenderInline{SPAN} still exist. This is the problem.

[Takashi Sakamoto]

Created attachment 164850 [details]
WIP

[WebKit Review Bot]

Comment on attachment 164850 [details]
WIP

Attachment 164850 [details] did not pass chromium-ews (chromium-xvfb):
Output: http://queues.webkit.org/results/13950225

New failing tests:
fast/invalid/007.html
fast/forms/formmove3.html
tables/mozilla/bugs/bug647.html
fast/table/table-continuation-outline-paint-crash.html
editing/deleting/delete-3800834-fix.html
fast/forms/preserveFormDuringResidualStyle.html
fast/dynamic/011.html
tables/mozilla/other/wa_table_tr_align.html
fast/invalid/004.html
fast/multicol/span/positioned-child-not-removed-crash.html
fast/invalid/003.html
fast/invalid/001.html
fast/invalid/019.html

[Takashi Sakamoto]

Created attachment 165541 [details]
WIP

[Takashi Sakamoto]

Created attachment 165555 [details]
WIP

[Build Bot]

Comment on attachment 165555 [details]
WIP

Attachment 165555 [details] did not pass mac-ews (mac):
Output: http://queues.webkit.org/results/14002695

New failing tests:
fast/invalid/007.html
fast/table/table-continuation-outline-paint-crash.html
tables/mozilla/bugs/bug647.html
fast/forms/formmove3.html
editing/deleting/delete-3800834-fix.html
fast/forms/preserveFormDuringResidualStyle.html
fast/dynamic/011.html
fast/invalid/004.html
fast/invalid/003.html
fast/invalid/001.html
fast/invalid/019.html

[Takashi Sakamoto]

Created attachment 165575 [details]
WIP

[Build Bot]

Comment on attachment 165575 [details]
WIP

Attachment 165575 [details] did not pass mac-ews (mac):
Output: http://queues.webkit.org/results/14031040

New failing tests:
fast/forms/formmove3.html
fast/forms/preserveFormDuringResidualStyle.html

[Takashi Sakamoto]

Created attachment 166130 [details]
Patch

[Abhishek Arya]

This bug is c#24 https://bugs.webkit.org/show_bug.cgi?id=74976#c24. I am on vacation, but i will back by Monday/Tuesday. The patch looks pretty complicated for such a change. You might wanna see bug 74976 and its patch to get ideas for easy removal. Otherwise, lets chat when i come back.

[Abhishek Arya]

Comment on attachment 166130 [details]
Patch

Looking more this looks really complicated and will not cover all the cases. if we just remove the block that splits the inline, then we will still have this problem. [try <i>A<div id=div1>B</div>C</i> and then do document.body.offsetTop; div1.parentNode.removeChild(div1).] When the div is removed, the renderinline and its continuation should be merged and both A and C should be under one RenderInline. Your patch only covers the moving case and in the example above, we are not moving any children between the inline and its continuation. Also, your patch makes the things slow since stuff gets moved between prev and next much more often. What you probably need to do is see about hooking stuff near the ->setContinuation calls added in 
http://trac.webkit.org/changeset/120477. We already cleanup the empty block continuation there.