Enable conditional directives by default.

pkg/compiler/lib/compiler_new.dart

Index: pkg/compiler/lib/compiler_new.dart
diff --git a/pkg/compiler/lib/compiler_new.dart b/pkg/compiler/lib/compiler_new.dart
index fa405da5323bd51b157feb77d11e7bff8084f30e..3f3f905c78752b157895bdc5a7be7d14854526a1 100644
--- a/pkg/compiler/lib/compiler_new.dart
+++ b/pkg/compiler/lib/compiler_new.dart
@@ -178,9 +178,6 @@ class CompilerOptions {
   /// reason for why an assertion fails. (experimental)
   final bool enableAssertMessage;
 
-  /// Whether to enable the experimental conditional directives feature.
-  final bool enableConditionalDirectives;
-
   /// Whether the user specified a flag to allow the use of dart:mirrors. This
   /// silences a warning produced by the compiler.
   final bool enableExperimentalMirrors;
@@ -313,8 +310,6 @@ class CompilerOptions {
         emitJavaScript: !(_hasOption(options, '--output-type=dart') ||
             _hasOption(options, '--output-type=dart-multi')),
         enableAssertMessage: _hasOption(options, Flags.enableAssertMessage),
-        enableConditionalDirectives:
-            _hasOption(options, Flags.conditionalDirectives),
         enableExperimentalMirrors:
             _hasOption(options, Flags.enableExperimentalMirrors),
         enableMinification: _hasOption(options, Flags.minify),
@@ -376,7 +371,6 @@ class CompilerOptions {
       bool dumpInfo: false,
       bool emitJavaScript: true,
       bool enableAssertMessage: false,
-      bool enableConditionalDirectives: false,
       bool enableExperimentalMirrors: false,
       bool enableMinification: false,
       bool enableNativeLiveTypeAnalysis: true,
@@ -441,7 +435,6 @@ class CompilerOptions {
         dumpInfo: dumpInfo,
         emitJavaScript: emitJavaScript,
         enableAssertMessage: enableAssertMessage,
-        enableConditionalDirectives: enableConditionalDirectives,
         enableExperimentalMirrors: enableExperimentalMirrors,
         enableMinification: enableMinification,
         enableNativeLiveTypeAnalysis: enableNativeLiveTypeAnalysis,
@@ -486,7 +479,6 @@ class CompilerOptions {
       this.dumpInfo: false,
       this.emitJavaScript: true,
       this.enableAssertMessage: false,
-      this.enableConditionalDirectives: false,
       this.enableExperimentalMirrors: false,
       this.enableMinification: false,
       this.enableNativeLiveTypeAnalysis: false,