Don't trust bounding client rects for characters

In some cases, on wrapping points, they span the whole line

Issue codemirror#4097

Author: marijnh

lib/codemirror.js

@@ -2688,6 +2688,16 @@
     return {node: node, start: start, end: end, collapse: collapse, coverStart: mStart, coverEnd: mEnd};
   }
 
+  function getUsefulRect(rects, bias) {
+    var rect = nullRect
+    if (bias == "left") for (var i = 0; i < rects.length; i++) {
+      if ((rect = rects[i]).left != rect.right) break
+    } else for (var i = rects.length - 1; i >= 0; i--) {
+      if ((rect = rects[i]).left != rect.right) break
+    }
+    return rect
+  }
+
   function measureCharInner(cm, prepared, ch, bias) {
     var place = nodeAndOffsetInLineMap(prepared.map, ch, bias);
     var node = place.node, start = place.start, end = place.end, collapse = place.collapse;
@@ -2697,17 +2707,10 @@
       for (var i = 0; i < 4; i++) { // Retry a maximum of 4 times when nonsense rectangles are returned
         while (start && isExtendingChar(prepared.line.text.charAt(place.coverStart + start))) --start;
         while (place.coverStart + end < place.coverEnd && isExtendingChar(prepared.line.text.charAt(place.coverStart + end))) ++end;
-        if (ie && ie_version < 9 && start == 0 && end == place.coverEnd - place.coverStart) {
+        if (ie && ie_version < 9 && start == 0 && end == place.coverEnd - place.coverStart)
           rect = node.parentNode.getBoundingClientRect();
-        } else if (ie && cm.options.lineWrapping) {
-          var rects = range(node, start, end).getClientRects();
-          if (rects.length)
-            rect = rects[bias == "right" ? rects.length - 1 : 0];
-          else
-            rect = nullRect;
-        } else {
-          rect = range(node, start, end).getBoundingClientRect() || nullRect;
-        }
+        else
+          rect = getUsefulRect(range(node, start, end).getClientRects(), bias)
         if (rect.left || rect.right || start == 0) break;
         end = start;
         start = start - 1;