Ignore files generated by the Editor.

sdk/lib/_internal/pub/lib/src/barback/build_environment.dart

Index: sdk/lib/_internal/pub/lib/src/barback/build_environment.dart
diff --git a/sdk/lib/_internal/pub/lib/src/barback/build_environment.dart b/sdk/lib/_internal/pub/lib/src/barback/build_environment.dart
index 9e1467b071a00811e382b5d860bd081a349ee377..af2eae8c906043bad774c0258d8914ed871e643a 100644
--- a/sdk/lib/_internal/pub/lib/src/barback/build_environment.dart
+++ b/sdk/lib/_internal/pub/lib/src/barback/build_environment.dart
@@ -221,15 +221,18 @@ class BuildEnvironment {
           var parts = path.split(event.path);
           if (parts.contains("packages") || parts.contains("assets")) return;
 
-          // Skip ".js" files that were (most likely) compiled from nearby
-          // ".dart" files. These are created by the Editor's "Run as
-          // JavaScript" command and are written directly into the package's
-          // directory. When pub's dart2js transformer then tries to create the
-          // same file name, we get a build error. To avoid that, just don't
-          // consider that file to be a source.
-          // TODO(rnystrom): Remove this when the Editor no longer generates
-          // .js files. See #15859.
+          // Skip files that were (most likely) compiled from nearby ".dart"
+          // files. These are created by the Editor's "Run as JavaScript"
+          // command and are written directly into the package's directory.
+          // When pub's dart2js transformer then tries to create the same file
+          // name, we get a build error. To avoid that, just don't consider
+          // that file to be a source.
+          // TODO(rnystrom): Remove these when the Editor no longer generates
+          // .js files and users have had enough time that they no longer have
+          // these files laying around. See #15859.
           if (event.path.endsWith(".dart.js")) return;
+          if (event.path.endsWith(".dart.js.map")) return;
+          if (event.path.endsWith(".dart.precompiled.js")) return;
 
           var id = new AssetId(package.name,
               path.relative(event.path, from: package.dir));
@@ -264,15 +267,18 @@ class BuildEnvironment {
         // Skip directories.
         if (!fileExists(entry)) continue;
 
-        // Skip ".js" files that were (most likely) compiled from nearby ".dart"
-        // files. These are created by the Editor's "Run as JavaScript" command
-        // and are written directly into the package's directory. When pub's
-        // dart2js transformer then tries to create the same file name, we get
-        // a build error. To avoid that, just don't consider that file to be a
-        // source.
-        // TODO(rnystrom): Remove this when the Editor no longer generates .js
-        // files. See #15859.
+        // Skip files that were (most likely) compiled from nearby ".dart"
+        // files. These are created by the Editor's "Run as JavaScript"
+        // command and are written directly into the package's directory.
+        // When pub's dart2js transformer then tries to create the same file
+        // name, we get a build error. To avoid that, just don't consider
+        // that file to be a source.
+        // TODO(rnystrom): Remove these when the Editor no longer generates
+        // .js files and users have had enough time that they no longer have
+        // these files laying around. See #15859.
         if (entry.endsWith(".dart.js")) continue;
+        if (entry.endsWith(".dart.js.map")) continue;
+        if (entry.endsWith(".dart.precompiled.js")) continue;
 
         var id = new AssetId(package.name,
             path.relative(entry, from: package.dir));