Blink doesnt respect the form.submit() when called on "focus" event for invalid form

Blink doent respect the form.submit() when called on focus event on invalid form.
    When an form submit button is clicked and if the form is invalid it will focus
    the field that shows error. If the user is calling the form.submit() on focus event
    on that field then it should submit the form. But currently the form does not get
    submitted. This patch removes this bug by completely removing the variable
    "m_isSubmittingOrPreparingForSubmission".

in API "submit" which is always called after API "prepareForSubmission". Also the variable can more appropriately be renamed to "m_isSubmitting".

Bug=357101

Review URL: https://codereview.chromium.org/199633017

git-svn-id: svn://svn.chromium.org/blink/trunk@170520 bbb929c8-8fbe-4397-9dbb-9b2b20218538