Revert of RenderFlexibleBox should be treated as a candidate for visible position.

Revert of RenderFlexibleBox should be treated as a candidate for visible position. (patchset #1 id:1 of https://codereview.chromium.org/897633002/)

Reason for revert:
Revert for now until the fix is ready. Will also be reverted on release branch.

Original issue's description:
> RenderFlexibleBox should be treated as a candidate for visible position.
> 
> Visible selection in an editable area is recalculated whenever an inner value of div is changed.
> If the inner value is empty, the visible selection recalculated with DeleteSelectionCommand::m_endingPostion
> is not correct. Because RenderBlockFlow is only considered but not RenderFlexibleBox in Position::isCandidate
> so that a calculated ending VisiblePosition for an editable div having ‘display : flex’ goes weird
> and VisibleSelection is empty accordingly.
> 
> BUG=450617
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=189482

TBR=sigbjornf@opera.com,rego@igalia.com,shivamidow@gmail.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=450617
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=193212

[eae, 2015-04-06 19:41:58]

Created Revert of RenderFlexibleBox should be treated as a candidate for visible
position.

[commit-bot: I haz the power, 2015-04-06 19:42:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1060113002/1

[commit-bot: I haz the power, 2015-04-06 19:42:50]

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

[commit-bot: I haz the power, 2015-04-06 19:42:51]

Failed to apply patch for Source/core/dom/Position.cpp:
While running patch -p1 --forward --force --no-backup-if-mismatch;
  patching file Source/core/dom/Position.cpp
  Hunk #1 FAILED at 855.
  1 out of 1 hunk FAILED -- saving rejects to file
Source/core/dom/Position.cpp.rej

Patch:       Source/core/dom/Position.cpp
Index: Source/core/dom/Position.cpp
diff --git a/Source/core/dom/Position.cpp b/Source/core/dom/Position.cpp
index
eb069bf693e1814eb09806a0a67b6ac149b1bd91..e4d56f2eef5cf9056e96b40c1c478e6fed7ff663
100644
--- a/Source/core/dom/Position.cpp
+++ b/Source/core/dom/Position.cpp
@@ -855,7 +855,7 @@
     if (isHTMLHtmlElement(*m_anchorNode))
         return false;
 
-    if (renderer->isRenderBlockFlow() || renderer->isFlexibleBox()) {
+    if (renderer->isRenderBlockFlow()) {
         if (toRenderBlock(renderer)->logicalHeight() ||
isHTMLBodyElement(*m_anchorNode)) {
             if
(!Position::hasRenderedNonAnonymousDescendantsWithHeight(renderer))
                 return atFirstEditingPositionForNode() &&
!Position::nodeIsUserSelectNone(deprecatedNode());

[commit-bot: I haz the power, 2015-04-06 19:42:54]

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

[eae, 2015-04-06 20:39:29]

The CQ bit was checked by eae@chromium.org

[commit-bot: I haz the power, 2015-04-06 20:39:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1060113002/90001

[commit-bot: I haz the power, 2015-04-06 20:40:41]

Committed patchset #2 (id:90001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=193212

[changseok, 2015-04-09 04:23:10]

On 2015/04/06 20:40:41, I haz the power (commit-bot) wrote:
> Committed patchset #2 (id:90001) as
> https://src.chromium.org/viewvc/blink?view=rev&revision=193212

According to https://codereview.chromium.org/1057953002/#msg20
We can reland the original cl. 
How can I do it?
Do I need to submit another cl or is there any convenient way I don't know? =)