Address review comment

Author: odersky

compiler/src/dotty/tools/dotc/CompilationUnit.scala

@@ -43,6 +43,7 @@ class CompilationUnit protected (val source: SourceFile) {
    */
   var needsInlining: Boolean = false
 
+  /** Set to `true` if inliner added anonymous mirrors that need to be completed */
   var needsMirrorSupport: Boolean = false
 
   /** Will be set to `true` if contains `Quote`.