Add support for assert statements with messages to the analyzer.

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 0e8f9c831b9d99678f39e38a5996be780e3cc176..3f8dc4c5a0a6798651602e967c971a436b9cbb9e 100644
--- a/pkg/analyzer/lib/src/generated/engine.dart
+++ b/pkg/analyzer/lib/src/generated/engine.dart
@@ -556,7 +556,8 @@ abstract class AnalysisContext {
    * Perform work until the given [result] has been computed for the given
    * [target]. Return the computed value.
    */
-  Object /*V*/ computeResult(AnalysisTarget target, ResultDescriptor /*<V>*/ result);
+  Object /*V*/ computeResult(
+      AnalysisTarget target, ResultDescriptor /*<V>*/ result);
 
   /**
    * Notifies the context that the client is going to stop using this context.
@@ -729,7 +730,8 @@ abstract class AnalysisContext {
    * If the corresponding [target] does not exist, or the [result] is not
    * computed yet, then the default value is returned.
    */
-  Object /*V*/ getResult(AnalysisTarget target, ResultDescriptor /*<V>*/ result);
+  Object /*V*/ getResult(
+      AnalysisTarget target, ResultDescriptor /*<V>*/ result);
 
   /**
    * Return a list of the sources being analyzed in this context whose full path
@@ -1131,6 +1133,7 @@ class AnalysisContextImpl implements InternalAnalysisContext {
         (this._options.hint && !options.hint) ||
         this._options.preserveComments != options.preserveComments ||
         this._options.strongMode != options.strongMode ||
+        this._options.enableAssertMessage != options.enableAssertMessage ||
         this._options.enableStrictCallChecks !=
             options.enableStrictCallChecks ||
         this._options.enableSuperMixins != options.enableSuperMixins;
@@ -1158,6 +1161,7 @@ class AnalysisContextImpl implements InternalAnalysisContext {
     this._options.generateImplicitErrors = options.generateImplicitErrors;
     this._options.generateSdkErrors = options.generateSdkErrors;
     this._options.dart2jsHint = options.dart2jsHint;
+    this._options.enableAssertMessage = options.enableAssertMessage;
     this._options.enableStrictCallChecks = options.enableStrictCallChecks;
     this._options.enableSuperMixins = options.enableSuperMixins;
     this._options.hint = options.hint;
@@ -6185,6 +6189,11 @@ abstract class AnalysisOptions {
   bool get dart2jsHint;
 
   /**
+   * Return `true` to enable custom assert messages (DEP 37).
+   */
+  bool get enableAssertMessage;
+
+  /**
    * Return `true` if analysis is to include the new async support.
    */
   @deprecated // Always true
@@ -6318,6 +6327,12 @@ class AnalysisOptionsImpl implements AnalysisOptions {
   bool dart2jsHint = false;
 
   /**
+   * A flag indicating whether custom assert messages are to be supported (DEP
+   * 37).
+   */
+  bool enableAssertMessage = false;
+
+  /**
    * A flag indicating whether generic methods are to be supported (DEP 22).
    */
   bool enableGenericMethods = false;
@@ -6399,6 +6414,7 @@ class AnalysisOptionsImpl implements AnalysisOptions {
     analyzeFunctionBodiesPredicate = options.analyzeFunctionBodiesPredicate;
     cacheSize = options.cacheSize;
     dart2jsHint = options.dart2jsHint;
+    enableAssertMessage = options.enableAssertMessage;
     enableStrictCallChecks = options.enableStrictCallChecks;
     enableSuperMixins = options.enableSuperMixins;
     generateImplicitErrors = options.generateImplicitErrors;
@@ -6420,6 +6436,7 @@ class AnalysisOptionsImpl implements AnalysisOptions {
     analyzeFunctionBodiesPredicate = options.analyzeFunctionBodiesPredicate;
     cacheSize = options.cacheSize;
     dart2jsHint = options.dart2jsHint;
+    enableAssertMessage = options.enableAssertMessage;
     enableStrictCallChecks = options.enableStrictCallChecks;
     enableSuperMixins = options.enableSuperMixins;
     generateImplicitErrors = options.generateImplicitErrors;
@@ -9288,7 +9305,8 @@ class IncrementalAnalysisTask extends AnalysisTask {
     }
     // Produce an updated AST
     IncrementalParser parser = new IncrementalParser(
-        cache.source, scanner.tokenMap, AnalysisErrorListener.NULL_LISTENER);
+        cache.source, scanner.tokenMap, AnalysisErrorListener.NULL_LISTENER,
+        enableAssertMessage: context.analysisOptions.enableAssertMessage);
     _updatedUnit = parser.reparse(cache.resolvedUnit, scanner.leftToken,
         scanner.rightToken, cache.offset, cache.offset + cache.oldLength);
     // Update the resolution
@@ -9718,7 +9736,8 @@ class ParseDartTask extends AnalysisTask {
     //
     PerformanceStatistics.parse.makeCurrentWhile(() {
       RecordingErrorListener errorListener = new RecordingErrorListener();
-      Parser parser = new Parser(source, errorListener);
+      Parser parser = new Parser(source, errorListener,
+          enableAssertMessage: context.analysisOptions.enableAssertMessage);
       AnalysisOptions options = context.analysisOptions;
       parser.parseFunctionBodies =
           options.analyzeFunctionBodiesPredicate(source);