path: isAbsolute() should always return boolean
path: isAbsolute() should always return boolean

On Windows, path.isAbsolute() returns an empty string on failed cases.
This forces the return value to always be boolean.

Reviewed-by: Trevor Norris <9cb5491eb5770dd8e0bf77a8a0335abf5f0488c5@gmail.com>

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node