Enable messages in asserts 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 30d48e22e38ff32851287ad2a24936daabf05b1a..d6cc535812f0a084d8b69f2f088d992339dfb8ef 100644
--- a/pkg/analyzer/lib/src/context/context.dart
+++ b/pkg/analyzer/lib/src/context/context.dart
@@ -282,7 +282,6 @@ class AnalysisContextImpl implements InternalAnalysisContext {
         this._options.strongMode != options.strongMode ||
         this._options.enableAssertInitializer !=
             options.enableAssertInitializer ||
-        this._options.enableAssertMessage != options.enableAssertMessage ||
         this._options.enableLazyAssignmentOperators !=
             options.enableLazyAssignmentOperators ||
         ((options is AnalysisOptionsImpl)
@@ -307,7 +306,6 @@ class AnalysisContextImpl implements InternalAnalysisContext {
     this._options.generateSdkErrors = options.generateSdkErrors;
     this._options.dart2jsHint = options.dart2jsHint;
     this._options.enableAssertInitializer = options.enableAssertInitializer;
-    this._options.enableAssertMessage = options.enableAssertMessage;
     this._options.enableStrictCallChecks = options.enableStrictCallChecks;
     this._options.enableLazyAssignmentOperators =
         options.enableLazyAssignmentOperators;