fix(Compiler): Use correct defaults for Barback.

PiperOrigin-RevId: 161610752

Author: matanlurey

angular/lib/src/transform/transformer.dart

@@ -39,7 +39,6 @@ class AngularTransformerGroup extends TransformerGroup {
         settings,
         defaultTo: new CompilerFlags(
           genDebugInfo: settings.mode == BarbackMode.DEBUG,
-          useLegacyStyleEncapsulation: true,
         ),
       ),
     );

angular/lib/transform/codegen.dart

@@ -41,7 +41,6 @@ class CodegenTransformer extends TransformerGroup {
         settings,
         defaultTo: new CompilerFlags(
           genDebugInfo: settings.mode == BarbackMode.DEBUG,
-          useLegacyStyleEncapsulation: true,
         ),
       ),
     );

angular_compiler/lib/src/flags.dart

@@ -85,7 +85,7 @@ class CompilerFlags {
     this.entryPoints: const [],
     this.profileFor: Profile.none,
     this.useLegacyStyleEncapsulation: false,
-    this.usePlaceholder: false,
+    this.usePlaceholder: true,
   });
 
   /// Creates flags by parsing command-line arguments.