Support --use-kernel in memory_compiler

pkg/front_end/lib/src/fasta/source/source_loader.dart

Index: pkg/front_end/lib/src/fasta/source/source_loader.dart
diff --git a/pkg/front_end/lib/src/fasta/source/source_loader.dart b/pkg/front_end/lib/src/fasta/source/source_loader.dart
index 7a0500fb694aa33b9f7e7edc325cf260925cfa3d..84d4c3723c3320d5c3a07278f2d1883c1286a92a 100644
--- a/pkg/front_end/lib/src/fasta/source/source_loader.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_loader.dart
@@ -98,7 +98,10 @@ class SourceLoader<L> extends Loader<L> {
     Uri uri = library.fileUri;
     // TODO(sigmund): source-loader shouldn't check schemes, but defer to the
     // underlying file system to decide whether it is supported.
-    if (uri == null || uri.scheme != "file" && uri.scheme != "multi-root") {
+    if (uri == null ||
+        uri.scheme != "file" &&
+            uri.scheme != "multi-root" &&
+            uri.scheme != "memory") {

[Siggi Cherem (dart-lang), 2017/08/23 20:45:18]

If you don't mind, let's revert the change on this file.

I just sent https://codereview.chromium.org/3006483002/ which basically deletes
this check and delegates to the underlying filesystem to let it define what's
supported.

[Johnni Winther, 2017/08/24 06:47:54]

I thought this might provoke you to fix the issue ;)

       return deprecated_inputError(
           library.uri, -1, "Not found: ${library.uri}.");
     }