Make Analysis Server tests use MockSdk again.

pkg/analyzer/test/src/context/mock_sdk.dart

Index: pkg/analyzer/test/src/context/mock_sdk.dart
diff --git a/pkg/analyzer/test/src/context/mock_sdk.dart b/pkg/analyzer/test/src/context/mock_sdk.dart
index a2c882d15d8c6bc81bf7e01235715c09ee48a9d3..ef800f939e26a56a57e8db5b2c6beae3e1a4748e 100644
--- a/pkg/analyzer/test/src/context/mock_sdk.dart
+++ b/pkg/analyzer/test/src/context/mock_sdk.dart
@@ -119,6 +119,7 @@ library dart.core;
 import 'dart:async';
 
 class Object {
+  const Object() {}
   bool operator ==(other) => identical(this, other);
   String toString() => 'a string';
   int get hashCode => 0;
@@ -361,8 +362,8 @@ const double E = 2.718281828459045;
 const double PI = 3.1415926535897932;
 const double LN10 =  2.302585092994046;
 
-num/*=T*/ min/*<T extends num>*/(num/*=T*/ a, num/*=T*/ b) => null;
-num/*=T*/ max/*<T extends num>*/(num/*=T*/ a, num/*=T*/ b) => null;
+T min<T extends num>(T a, T b) => null;
+T max<T extends num>(T a, T b) => null;
 
 external double cos(num x);
 external double sin(num x);