Bug 1007709 - [Dialer][Call Screen] Create fluid size for contact name in the upper information panel

These could be written as:
```js
var minFontSize;
switch (scenario) {
case DIAL_PAD:
  minFontSize = _MIN_FONT_SIZE_DIAL_PAD;
  break;
...
}
return parseInt(minFontSize * _getDefaultFontSize());
```
This means less duplicated code.