VerticalOffset of 0 causes VerticalOffset of -4 or 8

[ryangreenhill]

Description

Due to the fact that if(0) is false, the following code in paper-dropdown-menu.html does not fire the return of opt_verticalOffset and instead returns 8 or -4.

_computeMenuVerticalOffset: function(noLabelFloat, opt_verticalOffset) {
          // Override offset if it's passed from the user.
          if (opt_verticalOffset) { return opt_verticalOffset; }

          // NOTE(cdata): These numbers are somewhat magical because they are
          // derived from the metrics of elements internal to `paper-input`'s
          // template. The metrics will change depending on whether or not the
          // input has a floating label.
          return noLabelFloat ? -4 : 8;
},

Expected outcome

I expect a verticalOffset of 0.

Actual outcome

I receive a verticalOffset of -4 or 8, depending on the state of noLabelFloat

Steps to reproduce

1. Put a 'paper-dropdown-menu' in the page. Set the 'verticalOffset' attribute of the 'paper-dropdown-menu' to '0'
2. Open the page in a web browser
3. Click the 'paper-dropdown-menu' element.