Revert "Add "load from .dill" file capability and run a white-box test."

tests/compiler/dart2js/memory_compiler.dart

Index: tests/compiler/dart2js/memory_compiler.dart
diff --git a/tests/compiler/dart2js/memory_compiler.dart b/tests/compiler/dart2js/memory_compiler.dart
index 400572524c5412ed1d4287bdac8747023d6b97b7..d3b183be08cda5c1f9a789a3732c74152387a927 100644
--- a/tests/compiler/dart2js/memory_compiler.dart
+++ b/tests/compiler/dart2js/memory_compiler.dart
@@ -80,11 +80,7 @@ Future<CompilationResult> runCompiler(
     PackagesDiscoveryProvider packagesDiscoveryProvider,
     void beforeRun(CompilerImpl compiler)}) async {
   if (entryPoint == null) {
-    if (options.contains('--read-dill')) {
-      entryPoint = Uri.parse('memory:main.dill');
-    } else {
-      entryPoint = Uri.parse('memory:main.dart');
-    }
+    entryPoint = Uri.parse('memory:main.dart');
   }
   CompilerImpl compiler = compilerFor(
       entryPoint: entryPoint,