Make Analyzer, VM and dart2js accept URI strings as part-of library identifier.

pkg/analyzer/test/src/context/context_test.dart

Index: pkg/analyzer/test/src/context/context_test.dart
diff --git a/pkg/analyzer/test/src/context/context_test.dart b/pkg/analyzer/test/src/context/context_test.dart
index 1f612b9f3aae1fbeb2a360982720fff6de357370..68617e1eb7f6c31d472475cfd167cc144efa98dd 100644
--- a/pkg/analyzer/test/src/context/context_test.dart
+++ b/pkg/analyzer/test/src/context/context_test.dart
@@ -766,8 +766,12 @@ library lib;
     Source partSource = addSource("/part.dart", "part of 'lib';");
     context.parseCompilationUnit(librarySource);
     List<AnalysisError> errors = context.computeErrors(partSource);
-    expect(errors, isNotNull);
-    expect(errors.length > 0, isTrue);
+    if (context.analysisOptions.enableUriInPartOf) {
+      // Should report that 'lib' isn't the correct URI.

[Brian Wilkerson, 2017/01/25 17:05:14]

Could you make this (and similar comments in other files) TODO comments and open
an issue for the missed cases?

[Lasse Reichstein Nielsen, 2017/01/26 10:39:13]

Done.

+    } else {
+      expect(errors, isNotNull);
+      expect(errors.length > 0, isTrue);
+    }
   }
 
   void test_computeErrors_dart_some() {