[TIMOB-26791] Windows: Ti.UI.View reports top/left/bottom/right values as Strings always

I'm in the process of updating our test suite to use the latest should.js library, which now uses a stricter equality check. As a result, the tests are now flagging a number of windows UI tests as failing due to comparisons against expected numeric values. (the comparison used to do == but now do === so won't coerce to Number) Turns out we're reporting string values for top/left/right/bottom always on Windows where we report Numbers on Android/iOS. The properties themselves are Number or String, so Strings can be valid but would typically be reported when followed by the "unit" (i.e. "px", "em", "%"). For parity's sake, I think it'd be good to report the values as Numbers when they're purely numeric/have no units explicitly attached.