Found by running tests under a version of PHP patched to report
case mismatches as E_STRICT errors.
User classes:
* MIMEsearchPage
* MostlinkedTemplatesPage
* SpecialBookSources
* UnwatchedpagesPage
Internal classes:
* DOMXPath
* stdClass
* XMLReader
Did not change:
* testautoLoadedcamlCLASS
* testautoloadedserializedclass
Change-Id: Idc8caa82cd6adb7bab44b142af2b02e15f0a89ee
PHP's "equal" (==) operator considers the integer 0 to be equal to
the string 'X', and when 'X' is converted to a number, it becomes 0.
Neither is desired here.
* Fail when an X is encountered while calculating the check digit.
(X can only occur as the check digit of an ISBN-10.)
* Fixed the check digit comparisons by adding an explicit string cast.
* Used the "identical" operator to make it more obvious that no type
juggling should take place during the comparisons.
* Added some test cases.
* Removed an outdated TODO.
Bug: 67021
Change-Id: I85f53c41f403a60340e9441757fe66b9764e623c
