Fix scrolling while dragging

This is the fix from Paula for #217

based on the firebase-analytics branch, so only merge after that PR (or cherry pick this commit)

ios/Podfile.lock

@@ -95,6 +95,6 @@ SPEC CHECKSUMS:
   GoogleUtilities: f895fde57977df4e0233edda0dbeac490e3703b6
   nanopb: 2901f78ea1b7b4015c860c2fdd1ea2fee1a18d48
 
-PODFILE CHECKSUM: 7ea7f79f063091643bd6a21d5d4b4e8981dda797
+PODFILE CHECKSUM: d5c223883d3d06483e7e9d419cc9560fba5781d5
 
 COCOAPODS: 1.8.4

src/editor/ScratchJr.js

@@ -235,6 +235,11 @@ export default class ScratchJr {
         } else {
             window.onmouseup = undefined;
         }
+        document.body.addEventListener('touchmove',
+            function (e) {
+                e.preventDefault();
+            },
+            {passive: false});
     }
 
     static unfocus (evt) {