(ddk modular test) exclude sources from dill files.

This fixes the issue we had with shared/diamond depedencies.  This also matches
more closely how DDK is invoked internally and externally.

While the change to use `--dart-sdk-summary` is not necessary, this brings the
API closer to how it is used elsewhere. It should be cleaned up in the future to
reuse the `--input-summary` flag instead.

Change-Id: Iec3695b5541ffaf7f5762a3d77f071a596237da1
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/119723
Reviewed-by: Nicholas Shahan <nshahan@google.com>
Commit-Queue: Sigmund Cherem <sigmund@google.com>

pkg/dev_compiler/test/modular_suite.dart

@@ -81,6 +81,9 @@ class SourceToSummaryDillStep implements IOModularStep {
       extraArgs = ['--packages-file', '$rootScheme:/.packages'];
     }
 
+    Module sdkModule =
+        module.isSdk ? module : module.dependencies.firstWhere((m) => m.isSdk);
+
     List<String> args = [
       _kernelWorkerScript,
       '--summary-only',
@@ -93,8 +96,14 @@ class SourceToSummaryDillStep implements IOModularStep {
       ...extraArgs,
       '--output',
       '${toUri(module, dillId)}',
+      if (!module.isSdk) ...[
+        '--dart-sdk-summary',
+        '${toUri(sdkModule, dillId)}',
+        '--exclude-non-sources',
+      ],
       ...(transitiveDependencies
-          .expand((m) => ['--input-linked', '${toUri(m, dillId)}'])),
+          .where((m) => !m.isSdk)
+          .expand((m) => ['--input-summary', '${toUri(m, dillId)}'])),
       ...(sources.expand((String uri) => ['--source', uri])),
       ...(flags.expand((String flag) => ['--enable-experiment', flag])),
     ];

tests/modular/diamond/a.dart

@@ -0,0 +1,3 @@
+import 'b.dart';
+
+var item = b;

tests/modular/diamond/b.dart

@@ -0,0 +1,3 @@
+class B {}
+
+var b = new B();

tests/modular/diamond/main.dart

@@ -0,0 +1,6 @@
+import 'b.dart';
+import 'a.dart';
+
+main() {
+  print([item, b]);
+}

tests/modular/diamond/modules.yaml

@@ -0,0 +1,3 @@
+dependencies:
+  main: [a, b]
+  a: b