Updated RTL related inline comments

Author: Brian Vaughn

src/createGridComponent.js

@@ -343,6 +343,9 @@ export default function createGridComponent({
  const { scrollLeft, scrollTop, scrollUpdateWasRequested } = this.state;
 
  if (scrollUpdateWasRequested && this._outerRef != null) {
+ // TRICKY According to the spec, scrollLeft should be negative for RTL aligned elements.
+ // This is not the case for all browsers though (e.g. Chrome reports values as positive, measured relative to the left).
+ // So we need to determine which browser behavior we're dealing with, and mimic it.
  const outerRef = ((this._outerRef: any): HTMLElement);
  if (direction === 'rtl') {
  const isNegative = isRTLOffsetNegative();
@@ -728,8 +731,9 @@ export default function createGridComponent({
  const isNegative = isRTLOffsetNegative();
 
  // TRICKY According to the spec, scrollLeft should be negative for RTL aligned elements.
- // Chrome does not seem to adhere; its scrollLeft values are positive (measured relative to the left).
- // See https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollLeft
+ // This is not the case for all browsers though (e.g. Chrome reports values as positive, measured relative to the left).
+ // It's also easier for this component if we convert offsets to the same format as they would be in for ltr.
+ // So the simplest solution is to determine which browser behavior we're dealing with, and convert based on it.
  if (isNegative) {
  calculatedScrollLeft = -scrollLeft;
  } else {

src/createListComponent.js

@@ -238,6 +238,9 @@ export default function createListComponent({
  // TODO Deprecate direction "horizontal"
  if (direction === 'horizontal' || layout === 'horizontal') {
  if (direction === 'rtl') {
+ // TRICKY According to the spec, scrollLeft should be negative for RTL aligned elements.
+ // This is not the case for all browsers though (e.g. Chrome reports values as positive, measured relative to the left).
+ // So we need to determine which browser behavior we're dealing with, and mimic it.
  const isNegative = isRTLOffsetNegative();
  if (isNegative) {
  outerRef.scrollLeft = -scrollOffset;
@@ -512,8 +515,9 @@ export default function createListComponent({
  const isNegative = isRTLOffsetNegative();
 
  // TRICKY According to the spec, scrollLeft should be negative for RTL aligned elements.
- // Chrome does not seem to adhere; its scrollLeft values are positive (measured relative to the left).
- // See https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollLeft
+ // This is not the case for all browsers though (e.g. Chrome reports values as positive, measured relative to the left).
+ // It's also easier for this component if we convert offsets to the same format as they would be in for ltr.
+ // So the simplest solution is to determine which browser behavior we're dealing with, and convert based on it.
  if (isNegative) {
  scrollOffset = -scrollLeft;
  } else {