Fix 1up zoom wrong on start/entering fs

[cdrini]

Closes #1130 .

Also fixes runaway scroll when going FS on mobile from 2up.

Before on page load	After on page load

Tested on:

• Windows/FF
• Windows/Chrome
• Windows/Edge
• Android/FF
• Android/Chrome
• Android/Edge
• Android/Samsung Internet
• iPad 16.6/Safari
• iPad 16.6/Chrome
• Mac/Safari 16.5 (BS)
• iPhone 14/Safari

[codecov]

Codecov Report

Merging #1230 (d79e625) into master (20ab31e) will not change coverage.
Report is 1 commits behind head on master.
The diff coverage is 100.00%.

❗ Current head d79e625 differs from pull request most recent head dc92d0a. Consider uploading reports for the commit dc92d0a to get more accurate results

@@           Coverage Diff           @@
##           master    #1230   +/-   ##
=======================================
  Coverage   69.27%   69.27%           
=======================================
  Files          60       60           
  Lines        5103     5103           
  Branches     1069     1069           
=======================================
  Hits         3535     3535           
  Misses       1541     1541           
  Partials       27       27           

Files Changed	Coverage Δ
src/BookReader/Mode1Up.js	50.00% <100.00%> (ø)
src/BookReader/Mode1UpLit.js	80.91% <100.00%> (ø)