Implement method bindings for gap/row-gap/column-gap

Summary:
This adds method bindings for `YGNodeStyleSetGap` and `YGNodeStyleGetGap`.

Changelog:
[Genral][Added] - Implement method bindings for yoga gap/row-gap/column-gap

Reviewed By: yungsters

Differential Revision: D39922411

fbshipit-source-id: 6cbb4d352203d2ec92df162c3f2f2efd02bd9568

javascript/sources/entry-common.js

@@ -15,6 +15,7 @@ import type {
   Yoga$Wrap,
   Yoga$Align,
   Yoga$FlexDirection,
+  Yoga$Gap,
   Yoga$Direction,
   Yoga$PositionType,
   Yoga$Overflow,
@@ -155,6 +156,7 @@ export type Yoga$Node = {
   getFlexWrap(): Yoga$Wrap,
   getHeight(): Value,
   getJustifyContent(): Yoga$Justify,
+  getGap(gutter: Yoga$Gutter): Value,
   getMargin(edge: Yoga$Edge): Value,
   getMaxHeight(): Value,
   getMaxWidth(): Value,
@@ -189,6 +191,7 @@ export type Yoga$Node = {
   setHeightAuto(): void,
   setHeightPercent(height: number): void,
   setJustifyContent(justifyContent: Yoga$Justify): void,
+  setGap(gutter: Yoga$Gutter, gapLength: number): Value,
   setMargin(edge: Yoga$Edge, margin: number): void,
   setMarginAuto(edge: Yoga$Edge): void,
   setMarginPercent(edge: Yoga$Edge, margin: number): void,