Don't load assets unnecessarily when precompiling executables.

sdk/lib/_internal/pub/test/implicit_dependency_test.dart

 // Copyright (c) 2013, 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.
 
 import 'descriptor.dart' as d;
 import 'test_pub.dart';
 import '../lib/src/barback.dart' as barback;
 import '../lib/src/version.dart';
 
 main() {
   initConfig();
 
   forBothPubGetAndUpgrade((command) {
     integration("implicitly constrains it to versions pub supports", () {
-      servePackages([
-        packageMap("barback", current("barback")),
-        packageMap("stack_trace", previous("stack_trace")),
-        packageMap("stack_trace", current("stack_trace")),
-        packageMap("stack_trace", nextPatch("stack_trace")),
-        packageMap("stack_trace", max("stack_trace")),
-        packageMap("source_span", current("source_span"))
-      ]);
+      servePackages((builder) {
+        builder.serve("barback", current("barback"));
+        builder.serve("stack_trace", previous("stack_trace"));
+        builder.serve("stack_trace", current("stack_trace"));
+        builder.serve("stack_trace", nextPatch("stack_trace"));
+        builder.serve("stack_trace", max("stack_trace"));
+        builder.serve("source_span", current("source_span"));
+      });
 
       d.appDir({
         "barback": "any"
       }).create();
 
       pubCommand(command);
 
       d.packagesDir({"stack_trace": nextPatch("stack_trace")}).validate();
     });
 
     integration("pub's implicit constraint uses the same source and "
         "description as a dependency override", () {
-      servePackages([
-        packageMap("barback", current("barback")),
-        packageMap("stack_trace", nextPatch("stack_trace")),
-        packageMap("source_span", current("source_span"))
-      ]);
+      servePackages((builder) {
+        builder.serve("barback", current("barback"));
+        builder.serve("stack_trace", nextPatch("stack_trace"));
+        builder.serve("source_span", current("source_span"));
+      });
 
       d.dir("stack_trace", [
         d.libDir("stack_trace", 'stack_trace ${current("stack_trace")}'),
         d.libPubspec("stack_trace", current("stack_trace"))
       ]).create();
 
       d.dir(appPath, [
         d.pubspec({
           "name": "myapp",
           "dependencies": {"barback": "any"},
           "dependency_overrides": {
             "stack_trace": {"path": "../stack_trace"},
           }
         })
       ]).create();
 
       pubCommand(command);
 
       // Validate that we're using the path dependency version of stack_trace
       // rather than the hosted version.
       d.packagesDir({
         "stack_trace": current("stack_trace")
       }).validate();
     });
 
     integration("doesn't add a constraint if barback isn't in the package "
         "graph", () {
-      servePackages([
-        packageMap("stack_trace", previous("stack_trace")),
-        packageMap("stack_trace", current("stack_trace")),
-        packageMap("stack_trace", nextPatch("stack_trace")),
-        packageMap("stack_trace", max("stack_trace")),
-        packageMap("source_span", current("source_span"))
-      ]);
+      servePackages((builder) {
+        builder.serve("stack_trace", previous("stack_trace"));
+        builder.serve("stack_trace", current("stack_trace"));
+        builder.serve("stack_trace", nextPatch("stack_trace"));
+        builder.serve("stack_trace", max("stack_trace"));
+        builder.serve("source_span", current("source_span"));
+      });
 
       d.appDir({
         "stack_trace": "any"
       }).create();
 
       pubCommand(command);
 
       d.packagesDir({"stack_trace": max("stack_trace")}).validate();
     });
   });
 
   integration("unlocks if the locked version doesn't meet pub's "
       "constraint", () {
-    servePackages([
-      packageMap("barback", current("barback")),
-      packageMap("stack_trace", previous("stack_trace")),
-      packageMap("stack_trace", current("stack_trace")),
-      packageMap("source_span", current("source_span"))
-    ]);
+    servePackages((builder) {
+      builder.serve("barback", current("barback"));
+      builder.serve("stack_trace", previous("stack_trace"));
+      builder.serve("stack_trace", current("stack_trace"));
+      builder.serve("source_span", current("source_span"));
+    });
 
     d.appDir({"barback": "any"}).create();
 
     // Hand-create a lockfile to pin the package to an older version.
     createLockFile("myapp", hosted: {
       "barback": current("barback"),
       "stack_trace": previous("stack_trace")
     });
 
     pubGet();
@@ skipping 12 matching lines @@
   var constraint = barback.pubConstraints[packageName];
   return new Version(constraint.min.major, constraint.min.minor - 1, 0)
       .toString();
 }
 
 String nextPatch(String packageName) =>
     barback.pubConstraints[packageName].min.nextPatch.toString();
 
 String max(String packageName) =>
     barback.pubConstraints[packageName].max.toString();