Merge pull request #13151 from CyrusNajmabadi/listDecoupling

Decouple SyntaxList from SyntaxListBuilder.

src/Compilers/CSharp/Portable/Parser/Lexer.cs

@@ -303,22 +303,24 @@ internal SyntaxTriviaList LexSyntaxLeadingTrivia()
         {
             _leadingTriviaCache.Clear();
             this.LexSyntaxTrivia(afterFirstToken: TextWindow.Position > 0, isTrailing: false, triviaList: ref _leadingTriviaCache);
-            return new SyntaxTriviaList(default(Microsoft.CodeAnalysis.SyntaxToken), SyntaxList.List(_leadingTriviaCache), 0, 0);
+            return new SyntaxTriviaList(default(Microsoft.CodeAnalysis.SyntaxToken),
+                _leadingTriviaCache.ToListNode(), position: 0, index: 0);
         }
 
         internal SyntaxTriviaList LexSyntaxTrailingTrivia()
         {
             _trailingTriviaCache.Clear();
             this.LexSyntaxTrivia(afterFirstToken: true, isTrailing: true, triviaList: ref _trailingTriviaCache);
-            return new SyntaxTriviaList(default(Microsoft.CodeAnalysis.SyntaxToken), SyntaxList.List(_trailingTriviaCache), 0, 0);
+            return new SyntaxTriviaList(default(Microsoft.CodeAnalysis.SyntaxToken), 
+                _trailingTriviaCache.ToListNode(), position: 0, index: 0);
         }
 
         private SyntaxToken Create(ref TokenInfo info, SyntaxListBuilder leading, SyntaxListBuilder trailing, SyntaxDiagnosticInfo[] errors)
         {
             Debug.Assert(info.Kind != SyntaxKind.IdentifierToken || info.StringValue != null);
 
-            var leadingNode = SyntaxList.List(leading);
-            var trailingNode = SyntaxList.List(trailing);
+            var leadingNode = leading?.ToListNode();
+            var trailingNode = trailing?.ToListNode();
 
             SyntaxToken token;
             if (info.RequiresTextForXmlEntity)

src/Compilers/CSharp/Portable/Syntax/InternalSyntax/SyntaxList.cs

@@ -96,16 +96,6 @@ internal static SyntaxList List(ArrayElement<CSharpSyntaxNode>[] children)
             }
         }
 
-        internal static CSharpSyntaxNode List(SyntaxListBuilder builder)
-        {
-            if (builder != null)
-            {
-                return builder.ToListNode();
-            }
-
-            return null;
-        }
-
         internal abstract void CopyTo(ArrayElement<CSharpSyntaxNode>[] array, int offset);
 
         internal static CSharpSyntaxNode Concat(CSharpSyntaxNode left, CSharpSyntaxNode right)