Review first: Remove .NET Standard 2.1 Dependency & Fix Scripting Restore

Editor/Build/BuildProject.cs

@@ -375,6 +375,7 @@ private static bool BuildPlayer(string notification, BuildReleaseType releaseTyp
             string preBuildCompanyName = PlayerSettings.companyName;
             string preBuildProductName = PlayerSettings.productName;
             string preBuildBundleIdentifier = PlayerSettings.GetApplicationIdentifier(platform.targetGroup);
+            ScriptingImplementation preBuildImplementation = PlayerSettings.GetScriptingBackend(platform.targetGroup);
 
             // Configure environment settings to match the build configuration
             ConfigureEnvironment(releaseType, platform, architecture, scriptingBackend, distribution, buildTime);
@@ -426,6 +427,7 @@ private static bool BuildPlayer(string notification, BuildReleaseType releaseTyp
             PlayerSettings.companyName = preBuildCompanyName;
             PlayerSettings.productName = preBuildProductName;
             PlayerSettings.SetApplicationIdentifier(platform.targetGroup, preBuildBundleIdentifier);
+            PlayerSettings.SetScriptingBackend(platform.targetGroup, preBuildImplementation);
 
             return success;
         }

Editor/Build/Platform/BuildAndroid.cs

@@ -93,7 +93,7 @@ public override void Init()
                 variants = new BuildVariant[] {
                     new BuildVariant(_deviceTypeVariantId, EnumNamesToArray<AndroidArchitecture>()
                         .Skip(1)
-                        .SkipLast(1)
+                        .SkipLast()
                         .ToArray(),
                     0, true),
                     new BuildVariant(_textureCompressionVariantId, EnumNamesToArray<MobileTextureSubtarget>(), 0),

Editor/Build/Platform/BuildVariant.cs

@@ -24,7 +24,7 @@ public string variantKey
         {
             get
             {
-                return isFlag ? string.Join('+', flags) : values[selectedIndex];
+                return isFlag ? string.Join("+", flags) : values[selectedIndex];
             }
         }
 
@@ -64,7 +64,7 @@ List<int> ConvertFlagsToSelectedIndexList(int number)
 
         public override string ToString()
         {
-            return isFlag ? string.Join('+', flags) : values[selectedIndex];
+            return isFlag ? string.Join("+", flags) : values[selectedIndex];
         }
     }
 }

Editor/Generic/ExtensionMethods.cs

@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using System.IO;
 using System.Text.RegularExpressions;
 using UnityEditor;
@@ -70,5 +71,20 @@ public static void SafeDeleteArrayElementAtIndex(this SerializedProperty value,
             if (value.arraySize == oldLength)
                 value.DeleteArrayElementAtIndex(i);
         }
+
+        // Provided by Jon Skeet in https://stackoverflow.com/questions/969091/c-skiplast-implementation
+        public static IEnumerable<T> SkipLast<T>(this IEnumerable<T> source)
+        {
+            T previous = default(T);
+            bool first = true;
+            foreach (T element in source)
+            {
+                if (!first)
+                    yield return previous;
+
+                previous = element;
+                first = false;
+            }
+        }
     }
 }