Read SDK and patches from a JSON file.

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;
 
@@ skipping 118 matching lines @@
   void addSourceInformation(
       Uri uri, List<int> lineStarts, List<int> sourceCode) {
     String fileUri = relativizeUri(uri);
     uriToSource[fileUri] = new Source(lineStarts, sourceCode);
   }
 
   void read(Uri uri) {
     loader.read(uri);
   }
 
-  LibraryBuilder createLibraryBuilder(Uri uri, Uri fileUri) {
+  LibraryBuilder createLibraryBuilder(Uri uri, Uri fileUri, bool isPatch) {
     if (dillTarget.isLoaded) {
       var builder = dillTarget.loader.builders[uri];
       if (builder != null) {
         return builder;
       }
     }
-    return new KernelLibraryBuilder(uri, fileUri, loader);
+    return new KernelLibraryBuilder(uri, fileUri, loader, isPatch);
   }
 
   void forEachDirectSupertype(ClassBuilder cls, void f(NamedTypeBuilder type)) {
     TypeBuilder supertype = cls.supertype;
     if (supertype is NamedTypeBuilder) {
       f(supertype);
     } else if (supertype != null) {
       internalError("Unhandled: ${supertype.runtimeType}");
     }
     if (cls.interfaces != null) {
@@ skipping 188 matching lines @@
     }
     sb.writeln();
     await new File.fromUri(depsFile).writeAsString("$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);
+        new KernelLibraryBuilder(uri, fileUri, loader, false);
     loader.first = library;
     if (isFullProgram) {
       // If this is an outline, we shouldn't add an executable main
       // method. Similarly considerations apply to separate compilation. It
       // could also make sense to add a way to mark .dill files as having
       // compile-time errors.
       KernelProcedureBuilder mainBuilder = new KernelProcedureBuilder(null, 0,
           null, "main", null, null, ProcedureKind.Method, library, -1, -1, -1);
       library.addBuilder(mainBuilder.name, mainBuilder, -1);
       mainBuilder.body = new ExpressionStatement(
@@ skipping 341 matching lines @@
   }
   for (Constructor constructor in superclass.constructors) {
     if (constructor.name.name.isEmpty) {
       return constructor.function.requiredParameterCount == 0
           ? constructor
           : null;
     }
   }
   return null;
 }