Add initial support for parts to the incremental kernel generator.

pkg/front_end/lib/incremental_resolved_ast_generator.dart

Index: pkg/front_end/lib/incremental_resolved_ast_generator.dart
diff --git a/pkg/front_end/lib/incremental_resolved_ast_generator.dart b/pkg/front_end/lib/incremental_resolved_ast_generator.dart
index 79799de7e21f9f6084d5930a3801e61412553868..dd5e4c7fc6344439cb607a4443c4e75201c6f558 100644
--- a/pkg/front_end/lib/incremental_resolved_ast_generator.dart
+++ b/pkg/front_end/lib/incremental_resolved_ast_generator.dart
@@ -32,9 +32,9 @@ class DeltaLibraries {
 class ResolvedLibrary {
   final CompilationUnit definingCompilationUnit;
 
-  ResolvedLibrary(this.definingCompilationUnit);
+  final Map<Uri, CompilationUnit> partUnits;
 
-  // TODO(paulberry): add support for parts.
+  ResolvedLibrary(this.definingCompilationUnit, this.partUnits);
 }
 
 /// Interface for generating an initial resolved representation of a program and