Crash in CompositeEditCommand::ensureComposition

Crash in CompositeEditCommand::ensureComposition
https://bugs.webkit.org/show_bug.cgi?id=76207

Reviewed by Chang Shu.

Source/WebCore:

The crash was caused by TypingCommand not kept alive when new editing commands are executed
during adding more typings to the open last typing command since m_lastEditCommand is replaced
by the new command. Fixed the bug by keeping them alive a little longer with RefPtr.

Test: editing/execCommand/editing-command-while-executing-typing-command-crash.html

* editing/FrameSelection.cpp:
(WebCore::shouldStopBlinkingDueToTypingCommand):
(WebCore::FrameSelection::updateAppearance):
* editing/TypingCommand.cpp:
(WebCore::TypingCommand::deleteSelection):
(WebCore::TypingCommand::deleteKeyPressed):
(WebCore::TypingCommand::forwardDeleteKeyPressed):
(WebCore::TypingCommand::insertText):
(WebCore::TypingCommand::insertLineBreak):
(WebCore::TypingCommand::insertParagraphSeparatorInQuotedContent):
(WebCore::TypingCommand::insertParagraphSeparator):
(WebCore::TypingCommand::lastTypingCommandIfStillOpenForTyping):
(WebCore::TypingCommand::closeTyping):
* editing/TypingCommand.h:

LayoutTests:

Add a regression test.

* editing/execCommand/editing-command-while-executing-typing-command-crash-expected.txt: Added.
* editing/execCommand/editing-command-while-executing-typing-command-crash.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@105441 268f45cc-cd09-0410-ab3c-d52691b4dbfc