Refactor startsWithNewline() function to be a computed property

Author: gohanlon

Sources/SwiftSyntaxMacroExpansion/MacroSystem.swift

@@ -434,7 +434,7 @@ private class AttributeRemover: SyntaxRewriter {
     // Ensure that any horizontal whitespace trailing the attributes list is trimmed if the next
     // token starts a new line.
     if let nextToken = node.nextToken(viewMode: .sourceAccurate),
-      nextToken.leadingTrivia.startsWithNewline()
+      nextToken.leadingTrivia.startsWithNewline
     {
       if !triviaToAttachToNextToken.isEmpty {
         triviaToAttachToNextToken = triviaToAttachToNextToken.trimmingSuffix(while: \.isSpaceOrTab)
@@ -490,7 +490,7 @@ private extension Trivia {
     )
   }
 
-  func startsWithNewline() -> Bool {
+  var startsWithNewline: Bool {
     self.first?.isNewline ?? false
   }
 }