Fix 32-bit limitation showcased at

Stuk#777
which causes
Bug : uncompressed data size mismatch

Author: Ruben J. Garcia-Hernandez

dist/jszip.js

@@ -1856,7 +1856,7 @@ DataReader.prototype = {
             i;
         this.checkOffset(size);
         for (i = this.index + size - 1; i >= this.index; i--) {
-            result = (result << 8) + this.byteAt(i);
+            result = (result * 256) + this.byteAt(i);
         }
         this.index += size;
         return result;
@@ -11574,4 +11574,4 @@ module.exports = ZStream;
 
 }).call(this,typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {})
 },{}]},{},[10])(10)
-});
+});

lib/reader/DataReader.js

@@ -61,7 +61,7 @@ DataReader.prototype = {
             i;
         this.checkOffset(size);
         for (i = this.index + size - 1; i >= this.index; i--) {
-            result = (result << 8) + this.byteAt(i);
+            result = (result * 256) + this.byteAt(i);
         }
         this.index += size;
         return result;