Enable conditional directives by default.

pkg/analyzer/lib/src/context/context.dart

Index: pkg/analyzer/lib/src/context/context.dart
diff --git a/pkg/analyzer/lib/src/context/context.dart b/pkg/analyzer/lib/src/context/context.dart
index d2659baf50c4ab302d1c92cf233bc72c992fd65e..1d4a6943f07ad9b6caa06f51d8a6ba2676e40ccb 100644
--- a/pkg/analyzer/lib/src/context/context.dart
+++ b/pkg/analyzer/lib/src/context/context.dart
@@ -269,8 +269,6 @@ class AnalysisContextImpl implements InternalAnalysisContext {
             options.enableStrictCallChecks ||
         this._options.enableGenericMethods != options.enableGenericMethods ||
         this._options.enableAsync != options.enableAsync ||
-        this._options.enableConditionalDirectives !=
-            options.enableConditionalDirectives ||
         this._options.enableSuperMixins != options.enableSuperMixins;
     int cacheSize = options.cacheSize;
     if (this._options.cacheSize != cacheSize) {
@@ -285,8 +283,6 @@ class AnalysisContextImpl implements InternalAnalysisContext {
     this._options.enableAssertMessage = options.enableAssertMessage;
     this._options.enableStrictCallChecks = options.enableStrictCallChecks;
     this._options.enableAsync = options.enableAsync;
-    this._options.enableConditionalDirectives =
-        options.enableConditionalDirectives;
     this._options.enableSuperMixins = options.enableSuperMixins;
     this._options.enableTiming = options.enableTiming;
     this._options.hint = options.hint;