Disable NonAsciiCharacter Rule on verbatim strings

The rewriting logic we have for verbatim strings is incorrect, since
you can not use Unicode excape sequences inside them.  Issue 39 tracks
the correct fix, but for now, we'll just disable the rule on these sorts
of strings.

Author: ellismg

src/Microsoft.DotNet.CodeFormatting.Tests/Rules/NonAsciiCharactersAreEscapedInLiteralsRuleTests.cs

@@ -36,21 +36,22 @@ public void DoNotAllowUnicodeInLiterals()
 class Test
 {{
     public static readonly string BadString = ""This has {0} and {1}, which are both bad."";
-    public static readonly string AnotherBadString = @""This has {0} and {1}, which are both bad."";
+    public static readonly string AnotherBadString = @""This has {0} and {1}, which are both bad, but we don't rewrite yet."";
     public const char BadChar = '{0}';
 }}
 ", '\u2713', "\U0001F308");
 
-            var expected = @"
+            var expected = string.Format(@"
 using System;
 
 class Test
-{
+{{
     public static readonly string BadString = ""This has \u2713 and \U0001F308, which are both bad."";
-    public static readonly string AnotherBadString = @""This has \u2713 and \U0001F308, which are both bad."";
+    public static readonly string AnotherBadString = @""This has {0} and {1}, which are both bad, but we don't rewrite yet."";
     public const char BadChar = '\u2713';
-}
-";
+}}
+", '\u2713', "\U0001F308");
+
             Verify(text, expected);
         }
 

src/Microsoft.DotNet.CodeFormatting/Rules/NonAsciiCharactersAreEscapedInLiteralsRule.cs

@@ -51,6 +51,13 @@ private static SyntaxNode RewriteStringLiteralExpression(LiteralExpressionSyntax
             {
                 Debug.Assert(node.CSharpKind() == SyntaxKind.StringLiteralExpression);
 
+                if (node.Token.IsVerbatimStringLiteral())
+                {
+                    // We do not correctly rewrite verbatim string literals yet.  Once Issue 39 is
+                    // fixed we can remove this early out.
+                    return node;
+                }
+
                 if (HasNonAsciiCharacters(node.Token.Text))
                 {
                     string convertedText = EscapeNonAsciiCharacters(node.Token.Text);