Resolving floating point values for getSize in IE10

Changing bot.dom.getClientRect() to force return of integer sizes for each
dimension of the rectangle.
Exposing bot.inject.unwrapValue
Updating injectible atoms to be aware of window context

This allows the functions in dom.js and action.js to be able to take an
optional window argument. If omitted, the functions use the top-level
window context.