update pdf text layer builder with improvements from pdfjs 1.0.1040

services/web/public/coffee/ide/pdfng/directives/pdfTextLayer.coffee

@@ -142,13 +142,17 @@ define [
 					if width > 0
 						textLayerFrag.appendChild textDiv
 
+						if textDiv.dataset.canvasWidth?
 							# Dataset values come of type string.
-						textScale = textDiv.dataset.canvasWidth / width
+							textScale = textDiv.dataset.canvasWidth / width;
+							transform = 'scaleX(' + textScale + ')'
+						else
+							transform = ''
 						rotation = textDiv.dataset.angle
-						transform = 'scale(' + textScale + ', 1)'
-						transform = 'rotate(' + rotation + 'deg) ' + transform	if rotation
+						if rotation
+							transform = 'rotate(' + rotation + 'deg) ' + transform
+						if transform
 							CustomStyle.setProp 'transform', textDiv, transform
-						CustomStyle.setProp 'transformOrigin', textDiv, '0% 0%'
 					i++
 				@textLayerDiv.appendChild textLayerFrag
 				return
@@ -195,6 +199,10 @@ define [
 
 				# Storing into dataset will convert number into string.
 				textDiv.dataset.angle = angle * (180 / Math.PI)	if angle isnt 0
+				# We don't bother scaling single-char text divs, because it has very
+				# little effect on text highlighting. This makes scrolling on docs with
+				# lots of such divs a lot faster.
+				if textDiv.textContent.length > 1
 					if style.vertical
 						textDiv.dataset.canvasWidth = geom.height * @viewport.scale
 					else

services/web/public/js/libs/pdfListView/TextLayer.css

@@ -19,6 +19,11 @@
   white-space: pre;
   cursor: text;
   pointer-events: auto;
+  -webkit-transform-origin: 0% 0%;
+  -moz-transform-origin: 0% 0%;
+  -o-transform-origin: 0% 0%;
+  -ms-transform-origin: 0% 0%;
+  transform-origin: 0% 0%;
 }
 .plv-text-layer > div::selection {
   background:rgba(0,0,255,0.3);