Move patch file generation to fasta.

pkg/front_end/lib/src/fasta/kernel/kernel_target.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library fasta.kernel_target;
 
 import 'dart:async' show Future;
 
 import 'dart:io' show File, IOSink;
 
@@ skipping 253 matching lines @@
       }
       if (uri == null) return program;
       return await writeLinkedProgram(uri, program, isFullProgram: true);
     } on InputError catch (e) {
       return handleInputError(uri, e, isFullProgram: true);
     } catch (e, s) {
       return reportCrash(e, s, loader?.currentUriForCrashReporting);
     }
   }
 
-  Future writeDepsFile(Uri output, Uri depsFile) async {
+  Future writeDepsFile(Uri output, Uri depsFile,
+      {Iterable<Uri> extraDependencies}) async {
+    Uri base = depsFile.resolve(".");
+    String toRelativeFilePath(Uri uri) {
+      return Uri.parse(relativizeUri(uri, base: base)).toFilePath();
+    }
+
     if (loader.first == null) return null;
     StringBuffer sb = new StringBuffer();
-    Uri base = depsFile.resolve(".");
-    sb.write(Uri.parse(relativizeUri(output, base: base)).toFilePath());
+    sb.write(toRelativeFilePath(output));
     sb.write(":");
-    for (Uri dependency in loader.getDependencies()) {
+    Set<String> allDependencies = new Set<String>();
+    allDependencies.addAll(loader.getDependencies().map(toRelativeFilePath));
+    if (extraDependencies != null) {
+      allDependencies.addAll(extraDependencies.map(toRelativeFilePath));
+    }
+    for (String path in allDependencies) {
       sb.write(" ");
-      sb.write(Uri.parse(relativizeUri(dependency, base: base)).toFilePath());
+      sb.write(path);
     }
     sb.writeln();
     await new File.fromUri(depsFile).writeAsString("$sb");
+    ticker.logMs("Wrote deps file");
   }
 
   Program erroneousProgram(bool isFullProgram) {
     Uri uri = loader.first?.uri ?? Uri.parse("error:error");
     Uri fileUri = loader.first?.fileUri ?? uri;
     KernelLibraryBuilder library =
         new KernelLibraryBuilder(uri, fileUri, loader);
     loader.first = library;
     if (isFullProgram) {
       // If this is an outline, we shouldn't add an executable main
@@ skipping 361 matching lines @@
   }
   for (Constructor constructor in superclass.constructors) {
     if (constructor.name.name.isEmpty) {
       return constructor.function.requiredParameterCount == 0
           ? constructor
           : null;
     }
   }
   return null;
 }