Correct a few places where we are trying to do integer comparisons with None

[michaelDCurran]

Link to issue number:

Related to #9107

Summary of the issue:

In Python3, it is no longer valid to compair a number with None with operators such as less-than or greater-than.
Our codebase does this in quite a few places.
Most notably at the moment are places that affect:

• Internet Explorer support
• table support.

Description of how this pull request fixes the issue:

• Internet explorer support: ensure that event_objectID is not None before checking if greater than 0.
• speech: when fetching rowSpan and columnSpan, force these values to 1 if they are 0 or None, as a table cell that has no rowSpan can be assumed to have a rowSpan of 1.

Testing performed:

• Tables can be spoken and navigated in Firefox in this
  test case
• Opening and reading any page in Internet Explorer now works again.

Known issues with pull request:

I'm sure there are many more places we need to check, but these will really only be found either through prolonged use, or through static type checking.

Change log entry:

None.