don't use C#6 language features for the time being

src/csharp/Facebook.CSSLayout.Tests/LayoutEngineTest.cs

@@ -9,7 +9,6 @@
 
 using System;
 using NUnit.Framework;
-using static Facebook.CSSLayout.CSSLayout;
 
 namespace Facebook.CSSLayout.Tests
 {
@@ -19,6 +18,13 @@ namespace Facebook.CSSLayout.Tests
  */
 public class LayoutEngineTest
 {
+    const int POSITION_LEFT = CSSLayout.POSITION_LEFT;
+    const int POSITION_TOP = CSSLayout.POSITION_TOP;
+    const int POSITION_RIGHT = CSSLayout.POSITION_RIGHT;
+    const int POSITION_BOTTOM = CSSLayout.POSITION_BOTTOM;
+    const int DIMENSION_HEIGHT = CSSLayout.DIMENSION_HEIGHT;
+    const int DIMENSION_WIDTH = CSSLayout.DIMENSION_WIDTH;
+    
     static readonly MeasureFunction sTestMeasureFunction = (node, width) =>
     {
         if (CSSConstants.IsUndefined(width)) {

src/csharp/Facebook.CSSLayout/CSSNode.cs

@@ -10,7 +10,6 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
-using static Facebook.CSSLayout.CSSLayout;
 
 namespace Facebook.CSSLayout
 {
@@ -27,6 +26,13 @@ namespace Facebook.CSSLayout
 
     public class CSSNode
     {
+        const int POSITION_LEFT = CSSLayout.POSITION_LEFT;
+        const int POSITION_TOP = CSSLayout.POSITION_TOP;
+        const int POSITION_RIGHT = CSSLayout.POSITION_RIGHT;
+        const int POSITION_BOTTOM = CSSLayout.POSITION_BOTTOM;
+        const int DIMENSION_WIDTH = CSSLayout.DIMENSION_WIDTH;
+        const int DIMENSION_HEIGHT = CSSLayout.DIMENSION_HEIGHT;
+
         enum LayoutState
         {
             /**
@@ -62,13 +68,19 @@ namespace Facebook.CSSLayout
         LayoutState mLayoutState = LayoutState.DIRTY;
 
         public int ChildCount
-            => mChildren.Count;
+        {
+            get { return mChildren.Count; }
+        }
 
         public CSSNode this[int i]
-            => mChildren[i];
+        {
+            get { return mChildren[i]; }
+        }
 
         public IEnumerable<CSSNode> Children
-            => mChildren;
+        {
+            get { return mChildren; }
+        }
 
         public void AddChild(CSSNode child)
         {
@@ -124,7 +136,9 @@ namespace Facebook.CSSLayout
         }
 
         public bool IsMeasureDefined
-            => mMeasureFunction != null;
+        {
+            get { return mMeasureFunction != null; }
+        }
 
         internal MeasureOutput measure(MeasureOutput measureOutput, float width)
         {
@@ -152,14 +166,18 @@ namespace Facebook.CSSLayout
          */
 
         public bool IsDirty
-            => mLayoutState == LayoutState.DIRTY;
+        {
+            get { return mLayoutState == LayoutState.DIRTY; }
+        }
 
         /**
          * See {@link LayoutState#HAS_NEW_LAYOUT}.
          */
 
         public bool HasNewLayout
-            => mLayoutState == LayoutState.HAS_NEW_LAYOUT;
+        {
+            get { return mLayoutState == LayoutState.HAS_NEW_LAYOUT; }
+        }
 
         internal protected void dirty()
         {
@@ -395,11 +413,30 @@ namespace Facebook.CSSLayout
             set { updateFloatValue(ref style.maxHeight, value); }
         }
 
-        public float LayoutX => layout.position[POSITION_LEFT];
-        public float LayoutY => layout.position[POSITION_TOP];
-        public float LayoutWidth => layout.dimensions[DIMENSION_WIDTH];
-        public float LayoutHeight => layout.dimensions[DIMENSION_HEIGHT];
-        public CSSDirection LayoutDirection => layout.direction;
+        public float LayoutX
+        {
+            get { return layout.position[POSITION_LEFT]; }
+        }
+
+        public float LayoutY
+        {
+            get { return layout.position[POSITION_TOP]; }
+        }
+
+        public float LayoutWidth
+        {
+            get { return layout.dimensions[DIMENSION_WIDTH]; }
+        }
+
+        public float LayoutHeight
+        {
+            get { return layout.dimensions[DIMENSION_HEIGHT]; }
+        }
+
+        public CSSDirection LayoutDirection
+        {
+            get { return layout.direction; }
+        }
 
         /**
          * Set a default padding (left/top/right/bottom) for this node.

src/csharp/Facebook.CSSLayout/Facebook.CSSLayout.csproj

@@ -24,6 +24,7 @@
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <LangVersion>5</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <DebugType>none</DebugType>

src/csharp/Facebook.CSSLayout/LayoutEngine.cs

@@ -9,7 +9,6 @@
 
 using System;
 using boolean = System.Boolean;
-using static Facebook.CSSLayout.CSSLayout;
 
 namespace Facebook.CSSLayout
 {
@@ -20,6 +19,13 @@ namespace Facebook.CSSLayout
 
     static class LayoutEngine
     {
+        const int POSITION_LEFT = CSSLayout.POSITION_LEFT;
+        const int POSITION_TOP = CSSLayout.POSITION_TOP;
+        const int POSITION_RIGHT = CSSLayout.POSITION_RIGHT;
+        const int POSITION_BOTTOM = CSSLayout.POSITION_BOTTOM;
+        const int DIMENSION_WIDTH = CSSLayout.DIMENSION_WIDTH;
+        const int DIMENSION_HEIGHT = CSSLayout.DIMENSION_HEIGHT;
+
         const int CSS_FLEX_DIRECTION_COLUMN =
             (int)CSSFlexDirection.Column;
         const int CSS_FLEX_DIRECTION_COLUMN_REVERSE =

src/csharp/Facebook.CSSLayout/MeasureOutput.cs

@@ -23,7 +23,14 @@ namespace Facebook.CSSLayout
         public readonly float Width;
         public readonly float Height;
 
-        internal float width => Width;
-        internal float height => Height;
+        internal float width
+        {
+            get { return Width; }
+        }
+
+        internal float height
+        {
+            get { return Height; }
+        }
     }
 }