Remove redundant code in d3.svg.brush.

Now that d3.mouse does the “right thing” for touch events, we don’t need code
that handles touch events specially.

d3.js

@@ -8114,7 +8114,7 @@ d3 = function() {
       g.selectAll(".extent,.e>rect,.w>rect").attr("height", yExtent[1] - yExtent[0]);
     }
     function brushstart() {
-      var target = this, eventTarget = d3.select(d3.event.target), event_ = event.of(target, arguments), g = d3.select(target), resizing = eventTarget.datum(), resizingX = !/^(n|s)$/.test(resizing) && x, resizingY = !/^(e|w)$/.test(resizing) && y, dragging = eventTarget.classed("extent"), dragRestore = d3_event_dragSuppress(), center, origin = mouse(), offset;
+      var target = this, eventTarget = d3.select(d3.event.target), event_ = event.of(target, arguments), g = d3.select(target), resizing = eventTarget.datum(), resizingX = !/^(n|s)$/.test(resizing) && x, resizingY = !/^(e|w)$/.test(resizing) && y, dragging = eventTarget.classed("extent"), dragRestore = d3_event_dragSuppress(), center, origin = d3.mouse(target), offset;
       var w = d3.select(d3_window).on("keydown.brush", keydown).on("keyup.brush", keyup);
       if (d3.event.changedTouches) {
         w.on("touchmove.brush", brushmove).on("touchend.brush", brushend);
@@ -8137,10 +8137,6 @@ d3 = function() {
         type: "brushstart"
       });
       brushmove();
-      function mouse() {
-        var touches = d3.event.changedTouches;
-        return touches ? d3.touches(target, touches)[0] : d3.mouse(target);
-      }
       function keydown() {
         if (d3.event.keyCode == 32) {
           if (!dragging) {
@@ -8161,7 +8157,7 @@ d3 = function() {
         }
       }
       function brushmove() {
-        var point = mouse(), moved = false;
+        var point = d3.mouse(target), moved = false;
         if (offset) {
           point[0] += offset[0];
           point[1] += offset[1];

src/svg/brush.js

@@ -154,7 +154,7 @@ d3.svg.brush = function() {
         dragging = eventTarget.classed("extent"),
         dragRestore = d3_event_dragSuppress(),
         center,
-        origin = mouse(),
+        origin = d3.mouse(target),
         offset;
 
     var w = d3.select(d3_window)
@@ -198,11 +198,6 @@ d3.svg.brush = function() {
     event_({type: "brushstart"});
     brushmove();
 
-    function mouse() {
-      var touches = d3.event.changedTouches;
-      return touches ? d3.touches(target, touches)[0] : d3.mouse(target);
-    }
-
     function keydown() {
       if (d3.event.keyCode == 32) {
         if (!dragging) {
@@ -225,7 +220,7 @@ d3.svg.brush = function() {
     }
 
     function brushmove() {
-      var point = mouse(),
+      var point = d3.mouse(target),
           moved = false;
 
       // Preserve the offset for thick resizers.