remove "infer from overrides" option which is now obsolete

lib/src/compiler.dart

Index: lib/src/compiler.dart
diff --git a/lib/src/compiler.dart b/lib/src/compiler.dart
index 56e26e6b8c42ff311b972e52c9eac4768370224b..7899d0d916f96cb63df31bf06c07e7a4c0bee450 100644
--- a/lib/src/compiler.dart
+++ b/lib/src/compiler.dart
@@ -354,15 +354,11 @@ abstract class AbstractCompiler {
       [AnalysisErrorListener reporter])
       : context = context,
         options = options,
-        checker = createChecker(context.typeProvider, options.strongOptions,
+        checker = new CodeChecker(
+            new RestrictedRules(context.typeProvider,
+                options: options.strongOptions),
             reporter ?? AnalysisErrorListener.NULL_LISTENER);
 
-  static CodeChecker createChecker(TypeProvider typeProvider,
-      StrongModeOptions options, AnalysisErrorListener reporter) {
-    return new CodeChecker(
-        new RestrictedRules(typeProvider, options: options), reporter, options);
-  }
-
   String get outputDir => options.codegenOptions.outputDir;
   TypeRules get rules => checker.rules;
   AnalysisErrorListener get reporter => checker.reporter;