Fix all System.Text.Encodings.Web.Tests failures on ILC

More ParamNames testing...

Author: Atsushi Kanamori

src/System.Text.Encodings.Web/tests/System.Text.Encodings.Web.Tests.csproj

@@ -43,6 +43,14 @@
     <Compile Include="UnicodeRangeTests.cs" />
     <Compile Include="UrlEncoderTests.cs" />
   </ItemGroup>
+  <ItemGroup>
+    <Compile Include="$(CommonTestPath)\System\AssertExtensions.cs">
+      <Link>Common\System\AssertExtensions.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonTestPath)\System\PlatformDetection.cs">
+      <Link>Common\System\PlatformDetection.cs</Link>
+    </Compile>
+  </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="$(CommonTestPath)\Data\UnicodeData.8.0.txt">
       <LogicalName>UnicodeData.8.0.txt</LogicalName>

src/System.Text.Encodings.Web/tests/UnicodeRangeTests.cs

@@ -16,17 +16,15 @@ public class UnicodeRangeTests
         [InlineData(0x10000, 16)]
         public void Ctor_FailureCase_FirstCodePoint(int firstCodePoint, int rangeSize)
         {
-            var ex = Assert.Throws<ArgumentOutOfRangeException>(() => new UnicodeRange(firstCodePoint, rangeSize));
-            Assert.Equal("firstCodePoint", ex.ParamName);
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("firstCodePoint", () => new UnicodeRange(firstCodePoint, rangeSize));
         }
 
         [Theory]
         [InlineData(0x0100, -1)]
         [InlineData(0x0100, 0x10000)]
         public void Ctor_FailureCase_RangeSize(int firstCodePoint, int rangeSize)
         {
-            var ex = Assert.Throws<ArgumentOutOfRangeException>(() => new UnicodeRange(firstCodePoint, rangeSize));
-            Assert.Equal("length", ex.ParamName);
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("length", () => new UnicodeRange(firstCodePoint, rangeSize));
         }
 
         [Fact]
@@ -43,8 +41,7 @@ public void Ctor_SuccessCase()
         [Fact]
         public void FromSpan_FailureCase()
         {
-            var ex = Assert.Throws<ArgumentOutOfRangeException>(() => UnicodeRange.Create('\u0020', '\u0010'));
-            Assert.Equal("lastCharacter", ex.ParamName);
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("lastCharacter", () => UnicodeRange.Create('\u0020', '\u0010'));
         }
 
         [Fact]