Solve lib lint failure

Summary:
This diff solves `pod lib lint` failure.

We want to make a new yoga release, as I landed some changes in its podspec which solves the broken flipper build for xcode 11.

{F221612119}

Reviewed By: passy

Differential Revision: D18382588

fbshipit-source-id: efddfa3e93ca59b79b887d04f83407b004d9a199

Author: priteshrnandgaonkar

YogaKit/Source/YGLayoutExtensions.swift

@@ -5,6 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import yoga;
 postfix operator %
 
 extension Int {
@@ -29,15 +30,15 @@ extension YGValue : ExpressibleByIntegerLiteral, ExpressibleByFloatLiteral {
     public init(integerLiteral value: Int) {
         self = YGValue(value: Float(value), unit: .point)
     }
-	
+
     public init(floatLiteral value: Float) {
         self = YGValue(value: value, unit: .point)
     }
-  
+
     public init(_ value: Float) {
         self = YGValue(value: value, unit: .point)
     }
-  
+
     public init(_ value: CGFloat) {
         self = YGValue(value: Float(value), unit: .point)
     }