cps_ir: Clean up BuilderTask.

pkg/compiler/lib/src/compiler.dart

Index: pkg/compiler/lib/src/compiler.dart
diff --git a/pkg/compiler/lib/src/compiler.dart b/pkg/compiler/lib/src/compiler.dart
index e6d214c4ddf9faabf7493a9c3303b6eab1439a1f..2ba863e03eee8f1685d3169f2397b972b63a2ee5 100644
--- a/pkg/compiler/lib/src/compiler.dart
+++ b/pkg/compiler/lib/src/compiler.dart
@@ -1511,14 +1511,6 @@ abstract class Compiler implements DiagnosticListener {
     });
   }
 
-  bool irEnabled() {
-    // TODO(sigurdm,kmillikin): Support checked-mode checks.
-    return useCpsIr &&
-        backend is DartBackend &&
-        !enableTypeAssertions &&
-        !enableConcreteTypeInference;
-  }
-
   void computeMain() {
     if (mainApp == null) return;
 
@@ -1650,11 +1642,6 @@ abstract class Compiler implements DiagnosticListener {
 
     deferredLoadTask.onResolutionComplete(mainFunction);
 
-    if (irEnabled()) {
-      log('Building IR...');
-      irBuilder.buildNodes();
-    }
-
     log('Inferring types...');
     typesTask.onResolutionComplete(mainFunction);