[emacs bindings] Fix by-page scrolling bindings
[emacs bindings] Fix by-page scrolling bindings

Co-authored-by: Anthony Stewart <19397c66916640699ccfb2d3f0315882d2499ff1@google.com>
nightwing/CodeMirror,nightwing/CodeMirror,dperetti/CodeMirror,dperetti/CodeMirror,hackmdio/CodeMirror,nightwing/CodeMirror,dperetti/CodeMirror,hackmdio/CodeMirror,hackmdio/CodeMirror