Bug 1655391 - Make new stack only class handle deletion at current bl…

…ock boundary r=m_kato

This patch creates new stack only class, `HTMLEditor::AutoBlockElementsJoiner`
and splits `HTMLEditor::HandleDeleteCollapsedSelectionAtCurrentBlockBoundary()`
to considering the content nodes to be joined part and doing join the nodes
part.

Differential Revision: https://phabricator.services.mozilla.com/D85567

UltraBlame original commit: f3411b0d664666e80a9bfac96ee2d7b4ef9fba68

editor/libeditor/HTMLEditSubActionHandler.cpp

@@ -12736,21 +12736,44 @@ NS_ERROR_FAILURE
 )
 ;
 }
-EditActionResult
-result
-=
-HandleDeleteCollapsedSelectionAtCurrentBlockBoundary
+AutoBlockElementsJoiner
+joiner
+;
+if
 (
-aDirectionAndAmount
-MOZ_KnownLive
+!
+joiner
+.
+PrepareToDeleteCollapsedSelectionAtCurrentBlockBoundary
 (
 *
+this
+aDirectionAndAmount
+*
 scanFromStartPointResult
 .
 ElementPtr
 (
 )
+startPoint
+)
+)
+{
+return
+EditActionCanceled
+(
 )
+;
+}
+EditActionResult
+result
+=
+joiner
+.
+Run
+(
+*
+this
 startPoint
 )
 ;
@@ -12765,12 +12788,20 @@ Succeeded
 HTMLEditor
 :
 :
-HandleDeleteCollapsedSelectionAtCurrentBlockBoundary
+AutoBlockElementsJoiner
+:
+:
+Run
 (
 )
+failed
 "
 "
-failed
+(
+current
+block
+boundary
+)
 "
 )
 ;
@@ -15547,12 +15578,19 @@ return
 result
 ;
 }
-EditActionResult
+bool
 HTMLEditor
 :
 :
-HandleDeleteCollapsedSelectionAtCurrentBlockBoundary
+AutoBlockElementsJoiner
+:
+:
+PrepareToDeleteCollapsedSelectionAtCurrentBlockBoundary
 (
+const
+HTMLEditor
+&
+aHTMLEditor
 nsIEditor
 :
 :
@@ -15569,11 +15607,20 @@ aCaretPoint
 {
 MOZ_ASSERT
 (
+aHTMLEditor
+.
 IsEditActionDataAvailable
 (
 )
 )
 ;
+mMode
+=
+Mode
+:
+:
+JoinCurrentBlock
+;
 if
 (
 HTMLEditUtils
@@ -15587,18 +15634,9 @@ aCurrentBlockElement
 )
 {
 return
-EditActionCanceled
-(
-)
+false
 ;
 }
-nsCOMPtr
-<
-nsINode
->
-leftNode
-rightNode
-;
 if
 (
 aDirectionAndAmount
@@ -15610,76 +15648,100 @@ nsIEditor
 ePrevious
 )
 {
-leftNode
+mLeftContent
 =
+aHTMLEditor
+.
 GetPreviousEditableHTMLNode
 (
 aCurrentBlockElement
 )
 ;
-rightNode
+mRightContent
 =
 aCaretPoint
 .
-GetContainer
+GetContainerAsContent
 (
 )
 ;
 }
 else
 {
-rightNode
+mRightContent
 =
+aHTMLEditor
+.
 GetNextEditableHTMLNode
 (
 aCurrentBlockElement
 )
 ;
-leftNode
+mLeftContent
 =
 aCaretPoint
 .
-GetContainer
+GetContainerAsContent
 (
 )
 ;
 }
 if
 (
 !
-leftNode
+mLeftContent
 |
 |
 !
-rightNode
+mRightContent
 )
 {
 return
-EditActionCanceled
-(
-)
+false
 ;
 }
-if
-(
+return
+!
 HTMLEditor
 :
 :
 NodesInDifferentTableElements
 (
 *
-leftNode
+mLeftContent
 *
-rightNode
+mRightContent
 )
+;
+}
+EditActionResult
+HTMLEditor
+:
+:
+AutoBlockElementsJoiner
+:
+:
+HandleDeleteCollapsedSelectionAtCurrentBlockBoundary
+(
+HTMLEditor
+&
+aHTMLEditor
+const
+EditorDOMPoint
+&
+aCaretPoint
 )
 {
-return
-EditActionCanceled
+MOZ_ASSERT
 (
+mLeftContent
+)
+;
+MOZ_ASSERT
+(
+mRightContent
 )
 ;
-}
 EditActionResult
 result
 (
@@ -15696,70 +15758,31 @@ aCaretPoint
 AutoTrackDOMPoint
 tracker
 (
+aHTMLEditor
+.
 RangeUpdaterRef
 (
 )
 &
 pointToPutCaret
 )
 ;
-if
-(
-NS_WARN_IF
-(
-!
-leftNode
--
->
-IsContent
-(
-)
-)
-|
-|
-NS_WARN_IF
-(
-!
-rightNode
--
->
-IsContent
-(
-)
-)
-)
-{
-return
-EditActionResult
-(
-NS_ERROR_FAILURE
-)
-;
-}
 result
 |
 =
+aHTMLEditor
+.
 TryToJoinBlocksWithTransaction
 (
 MOZ_KnownLive
 (
 *
-leftNode
--
->
-AsContent
-(
-)
+mLeftContent
 )
 MOZ_KnownLive
 (
 *
-rightNode
--
->
-AsContent
-(
-)
+mRightContent
 )
 )
 ;
@@ -15799,6 +15822,8 @@ result
 nsresult
 rv
 =
+aHTMLEditor
+.
 CollapseSelectionTo
 (
 pointToPutCaret