Make TypingCommand::insertText() to take SelectionInDOMTree instead of VisibleSelection

This patch makes |TypingCommand::insertText()| to take |SelectionInDOMTree|
instead of |VisibleSelection| to reduce usage of |VisibleSelection| for
improving code health.

BUG=657237
TEST=n/a

Review-Url: https://codereview.chromium.org/2733183002
Cr-Commit-Position: refs/heads/master@{#455368}
void TypingCommand::updatePreservesTypingStyle(ETypingCommand commandType) {
  switch (commandType) {
    case DeleteSelection:
    case DeleteKey:
    case ForwardDeleteKey:
    case InsertParagraphSeparator:
    case InsertLineBreak:
      m_preservesTypingStyle = true;
      return;
    case InsertParagraphSeparatorInQuotedContent:
    case InsertText:
      m_preservesTypingStyle = false;
      return;
  }
  NOTREACHED();
  m_preservesTypingStyle = false;
}

void TypingCommand::updatePreservesTypingStyle(ETypingCommand commandType) {
  switch (commandType) {
    case DeleteSelection:
    case DeleteKey:
    case ForwardDeleteKey:
    case InsertParagraphSeparator:
    case InsertLineBreak:
      m_preservesTypingStyle = true;
      return;
    case InsertParagraphSeparatorInQuotedContent:
    case InsertText:
      m_preservesTypingStyle = false;
      return;
  }
  NOTREACHED();
  m_preservesTypingStyle = false;
}
