fix mouse wheel scroll delay problem

[mn297]

Removed the annoying delay when attempting to mouse wheel zoom while viewing a PDF, does not cause other issues. Tested with PDF Viewer extension for chrome https://chrome.google.com/webstore/detail/pdf-viewer/oemmndcbldboiebfnladdacbdfmadadm?hl=en

[Snuffleupagus]

Thanks for the PR, however we unfortunately cannot accept this.

Tested with PDF Viewer extension for chrome

Please note that the Firefox built-in PDF Viewer is the primary development target for this library.
Furthermore, this timeout was added for multiple reasons:

• Originally to fix issue Document zoomed if still scrolling and meta keys pressed. #7022, see also PR Prevents document zooming if still scrolling and meta keys pressed (Issue #7022) #7097.
• Then extended to fix bug 1503412, see Attempt to ignore mouse wheel zooming during tab switches (bug 1503412) #10351.