Introduce convenience methods into generated analysis server classes.

pkg/analysis_server/test/computer/error_test.dart

Index: pkg/analysis_server/test/computer/error_test.dart
diff --git a/pkg/analysis_server/test/computer/error_test.dart b/pkg/analysis_server/test/computer/error_test.dart
index fd4e1daf912030af3ae33f124e3f43fca7c0d07a..b64212ac09f1d1f99fa3b963066c809fe8388ce9 100644
--- a/pkg/analysis_server/test/computer/error_test.dart
+++ b/pkg/analysis_server/test/computer/error_test.dart
@@ -54,7 +54,7 @@ class AnalysisErrorTest {
 
   void test_fromEngine_hasCorrection() {
     when(engineError.correction).thenReturn('my correction');
-    AnalysisError error = analysisErrorFromEngine(lineInfo, engineError);
+    AnalysisError error = new AnalysisError.fromEngine(lineInfo, engineError);
     expect(error.toJson(), {
       SEVERITY: 'ERROR',
       TYPE: 'COMPILE_TIME_ERROR',
@@ -72,7 +72,7 @@ class AnalysisErrorTest {
 
   void test_fromEngine_noCorrection() {
     when(engineError.correction).thenReturn(null);
-    AnalysisError error = analysisErrorFromEngine(lineInfo, engineError);
+    AnalysisError error = new AnalysisError.fromEngine(lineInfo, engineError);
     expect(error.toJson(), {
       SEVERITY: 'ERROR',
       TYPE: 'COMPILE_TIME_ERROR',
@@ -89,7 +89,7 @@ class AnalysisErrorTest {
 
   void test_fromEngine_noLineInfo() {
     when(engineError.correction).thenReturn(null);
-    AnalysisError error = analysisErrorFromEngine(null, engineError);
+    AnalysisError error = new AnalysisError.fromEngine(null, engineError);
     expect(error.toJson(), {
       SEVERITY: 'ERROR',
       TYPE: 'COMPILE_TIME_ERROR',