[TIMOB-8328] Mobileweb: Ti.UI.Label doesn't handle string values for `fontSize`

Problem

Mobileweb does not translate string values for fontSize into the appropriate integer values. Android and iOS do this automatically. This likely impacts other properties, but this is how it surfaced for me.

Test Case

var win = Ti.UI.createWindow();
win.add(Ti.UI.createLabel({
    text: 'Hello, World!',
    font: {
        fontSize: '32'   // Will automatically become an integer on android and ios, does not on mobileweb
    }
}));
win.open();

The result on Android and iOS will be a label with a font size of 32. On mobileweb, I'm guessing it doesn't recognize the string value and then just uses the default font size to display the label. Changing '32' to simply 32 allows mobileweb to resize correctly.