[HTML5] Fix multi-touch input handling.

The code to populate the input data for WebAssembly was incorrectly
overriding values when multiple touches were present due to wrong
indexing.

(cherry picked from commit 470496d8d40e2f476fac4f72c0b69748b5370936)

platform/javascript/js/libs/library_godot_input.js

@@ -424,9 +424,9 @@ const GodotInput = {
 			for (let i = 0; i < touches.length; i++) {
 				const touch = touches[i];
 				const pos = GodotInput.computePosition(touch, rect);
-				GodotRuntime.setHeapValue(coords + (i * 2), pos[0], 'double');
-				GodotRuntime.setHeapValue(coords + (i * 2 + 8), pos[1], 'double');
-				GodotRuntime.setHeapValue(ids + i, touch.identifier, 'i32');
+				GodotRuntime.setHeapValue(coords + (i * 2) * 8, pos[0], 'double');
+				GodotRuntime.setHeapValue(coords + (i * 2 + 1) * 8, pos[1], 'double');
+				GodotRuntime.setHeapValue(ids + i * 4, touch.identifier, 'i32');
 			}
 			func(type, touches.length);
 			if (evt.cancelable) {