Enable conditional directives by default.

pkg/analyzer/lib/src/generated/engine.dart

Index: pkg/analyzer/lib/src/generated/engine.dart
diff --git a/pkg/analyzer/lib/src/generated/engine.dart b/pkg/analyzer/lib/src/generated/engine.dart
index 846b27bfe3379a2ea527fb068a59145df2f3e4ce..5878d8581873823cc8108cd9694253c1242a627c 100644
--- a/pkg/analyzer/lib/src/generated/engine.dart
+++ b/pkg/analyzer/lib/src/generated/engine.dart
@@ -1060,11 +1060,6 @@ abstract class AnalysisOptions {
   bool get enableAsync;
 
   /**
-   * Return `true` to enable interface libraries (DEP 40).
-   */
-  bool get enableConditionalDirectives;

[Brian Wilkerson, 2016/04/01 22:59:38]

To avoid a breaking change, this should not be deleted but should be marked as
deprecated.

[floitsch, 2016/04/13 14:50:00]

Done.

-
-  /**
    * Return `true` to enable generic methods (DEP 22).
    */
   bool get enableGenericMethods => null;
@@ -1199,11 +1194,6 @@ class AnalysisOptionsImpl implements AnalysisOptions {
   bool enableAsync = true;
 
   /**
-   * A flag indicating whether interface libraries are to be supported (DEP 40).
-   */
-  bool enableConditionalDirectives = false;

[Brian Wilkerson, 2016/04/01 22:59:38]

This should be replaced by a deprecated getter that always returns `true`, and a
deprecated setter that does nothing.

[floitsch, 2016/04/13 14:50:00]

Done.

-
-  /**
    * A flag indicating whether generic methods are to be supported (DEP 22).
    */
   bool enableGenericMethods = false;
@@ -1297,7 +1287,6 @@ class AnalysisOptionsImpl implements AnalysisOptions {
     dart2jsHint = options.dart2jsHint;
     enableAssertMessage = options.enableAssertMessage;
     enableAsync = options.enableAsync;
-    enableConditionalDirectives = options.enableConditionalDirectives;
     enableStrictCallChecks = options.enableStrictCallChecks;
     enableGenericMethods = options.enableGenericMethods;
     enableSuperMixins = options.enableSuperMixins;