[VIV-730] Fix dropdown calculation and complex track by

[xiata]

• Fixes positioning code for the dropdown. ui-select-detached hosed things up with position: fixed.
• removeGlobalHandlers and resetDropdown merged together since there is no reason not to do both.
• Rearranged some functions and variables.
• Aliasing of document.documentElement.
• Dont bother resetting position of dropdown on close.
• Fix setActiveIndexToSelected to handle track bys more complicated than track by key.id, supporting scoped properties such as track by option[col.colDef.field]

[Joel-Kornbluh]

1. In payroll grid when clicking ALT+DOWN to activate, the drop-down opens but isn't focused
2. When drop-down isn't appended to body, it will sometimes remain aligned to the top (See attachment below) which causes some weird behavior when searching

[xiata]

Fixed, calculateDropdownPosition needed a timeout in refreshItems.

[Joel-Kornbluh]

@xiata Great job on this!
Tested the the new implementation in different edge cases. Works a charm with automatic positioning.