Fix insertion point layout for text runs with multiple fragments
Fix insertion point layout for text runs with multiple fragments

Before this fix, if a TextRun containing an insertion point was split into
multiple ScannedText fragments, text layout would draw an insertion point
inside of each of the fragments.  This patch records the insertion point
position at most once per TextRun, and copies it only into the appropriate
ScannedText fragment.

splav/servo,emilio/servo,rnestler/servo,szeged/servo,DominoTree/servo,splav/servo,sadmansk/servo,nnethercote/servo,avadacatavra/servo,SimonSapin/servo,sadmansk/servo,paulrouget/servo,KiChjang/servo,emilio/servo,ConnorGBrewster/servo,ConnorGBrewster/servo,cbrewster/servo,thiagopnts/servo,mattnenterprise/servo,rnestler/servo,nnethercote/servo,nrc/servo,thiagopnts/servo,fiji-flo/servo,thiagopnts/servo,CJ8664/servo,rnestler/servo,ConnorGBrewster/servo,jimberlage/servo,dati91/servo,saneyuki/servo,mattnenterprise/servo,paulrouget/servo,peterjoel/servo,dsandeephegde/servo,avadacatavra/servo,eddyb/servo,steveklabnik/servo,dati91/servo,nnethercote/servo,sadmansk/servo,mattnenterprise/servo,fiji-flo/servo,peterjoel/servo,notriddle/servo,pyfisch/servo,cbrewster/servo,dsandeephegde/servo,saneyuki/servo,splav/servo,KiChjang/servo,canaltinova/servo,mbrubeck/servo,avadacatavra/servo,jimberlage/servo,szeged/servo,eddyb/servo,cbrewster/servo,thiagopnts/servo,eddyb/servo,splav/servo,jimberlage/servo,canaltinova/servo,nnethercote/servo,saneyuki/servo,DominoTree/servo,CJ8664/servo,KiChjang/servo,SimonSapin/servo,SimonSapin/servo,mbrubeck/servo,pyfisch/servo,paulrouget/servo,notriddle/servo,DominoTree/servo,mattnenterprise/servo,szeged/servo,anthgur/servo,nrc/servo,paulrouget/servo,SimonSapin/servo,upsuper/servo,ConnorGBrewster/servo,nrc/servo,nnethercote/servo,szeged/servo,notriddle/servo,szeged/servo,larsbergstrom/servo,ConnorGBrewster/servo,steveklabnik/servo,ConnorGBrewster/servo,paulrouget/servo,eddyb/servo,emilio/servo,mattnenterprise/servo,saneyuki/servo,larsbergstrom/servo,emilio/servo,dsandeephegde/servo,steveklabnik/servo,fiji-flo/servo,cbrewster/servo,szeged/servo,dati91/servo,jimberlage/servo,thiagopnts/servo,canaltinova/servo,SimonSapin/servo,CJ8664/servo,mbrubeck/servo,paulrouget/servo,larsbergstrom/servo,peterjoel/servo,saneyuki/servo,szeged/servo,avadacatavra/servo,emilio/servo,pyfisch/servo,peterjoel/servo,sadmansk/servo,DominoTree/servo,larsbergstrom/servo,dsandeephegde/servo,jimberlage/servo,pyfisch/servo,KiChjang/servo,saneyuki/servo,pyfisch/servo,notriddle/servo,nnethercote/servo,anthgur/servo,thiagopnts/servo,avadacatavra/servo,peterjoel/servo,peterjoel/servo,CJ8664/servo,emilio/servo,pyfisch/servo,pyfisch/servo,mbrubeck/servo,splav/servo,jimberlage/servo,sadmansk/servo,emilio/servo,dati91/servo,DominoTree/servo,mbrubeck/servo,KiChjang/servo,anthgur/servo,upsuper/servo,CJ8664/servo,larsbergstrom/servo,cbrewster/servo,rnestler/servo,steveklabnik/servo,mbrubeck/servo,steveklabnik/servo,paulrouget/servo,DominoTree/servo,upsuper/servo,nnethercote/servo,paulrouget/servo,dati91/servo,larsbergstrom/servo,ConnorGBrewster/servo,nnethercote/servo,dati91/servo,fiji-flo/servo,szeged/servo,mbrubeck/servo,anthgur/servo,SimonSapin/servo,ConnorGBrewster/servo,DominoTree/servo,steveklabnik/servo,cbrewster/servo,pyfisch/servo,peterjoel/servo,notriddle/servo,dati91/servo,canaltinova/servo,peterjoel/servo,CJ8664/servo,upsuper/servo,mattnenterprise/servo,splav/servo,nnethercote/servo,larsbergstrom/servo,avadacatavra/servo,mbrubeck/servo,splav/servo,pyfisch/servo,KiChjang/servo,DominoTree/servo,notriddle/servo,notriddle/servo,cbrewster/servo,szeged/servo,canaltinova/servo,rnestler/servo,saneyuki/servo,sadmansk/servo,canaltinova/servo,peterjoel/servo,fiji-flo/servo,splav/servo,jimberlage/servo,thiagopnts/servo,saneyuki/servo,jimberlage/servo,anthgur/servo,KiChjang/servo,peterjoel/servo,fiji-flo/servo,larsbergstrom/servo,emilio/servo,KiChjang/servo,dsandeephegde/servo,emilio/servo,paulrouget/servo,eddyb/servo,eddyb/servo,dsandeephegde/servo,KiChjang/servo,upsuper/servo,splav/servo,canaltinova/servo,saneyuki/servo,anthgur/servo,sadmansk/servo,anthgur/servo,fiji-flo/servo,larsbergstrom/servo,canaltinova/servo,eddyb/servo,thiagopnts/servo,saneyuki/servo,notriddle/servo,dsandeephegde/servo,dsandeephegde/servo,dati91/servo,rnestler/servo,sadmansk/servo,DominoTree/servo,DominoTree/servo,upsuper/servo,emilio/servo,nrc/servo,splav/servo,fiji-flo/servo,SimonSapin/servo,nnethercote/servo,notriddle/servo,steveklabnik/servo,szeged/servo,pyfisch/servo,rnestler/servo,KiChjang/servo,notriddle/servo,nrc/servo,paulrouget/servo,eddyb/servo,rnestler/servo,mattnenterprise/servo,CJ8664/servo,nrc/servo,CJ8664/servo,avadacatavra/servo,upsuper/servo,avadacatavra/servo,jimberlage/servo,nrc/servo,anthgur/servo,SimonSapin/servo,upsuper/servo,mattnenterprise/servo,cbrewster/servo,larsbergstrom/servo