Only set primary touch pointer when there are no other touches

removePrimaryTouch broken by removing extraneous touch identifier cloning
Fixes googlearchive/PointerGestures#15

src/touch.js

@@ -103,15 +103,16 @@
       return this.firstTouch === inTouch.identifier;
     },
     setPrimaryTouch: function(inTouch) {
-      if (this.firstTouch === null) {
+      // set primary touch if there no pointers, or the only pointer is the mouse
+      if (pointermap.size == 0 || (pointermap.size == 1 && pointermap.has(1))) {
         this.firstTouch = inTouch.identifier;
         this.firstXY = {X: inTouch.clientX, Y: inTouch.clientY};
         this.scrolling = false;
         this.cancelResetClickCount();
       }
     },
-    removePrimaryTouch: function(inTouch) {
-      if (this.isPrimaryTouch(inTouch)) {
+    removePrimaryPointer: function(inPointer) {
+      if (inPointer.isPrimary) {
         this.firstTouch = null;
         this.firstXY = null;
         this.resetClickCount();
@@ -291,7 +292,7 @@
     },
     cleanUpPointer: function(inPointer) {
       pointermap.delete(inPointer.pointerId);
-      this.removePrimaryTouch(inPointer);
+      this.removePrimaryPointer(inPointer);
     },
     // prevent synth mouse events from creating pointer events
     dedupSynthMouse: function(inEvent) {