Revert "Refactor Date implementation in VM."

lib/compiler/implementation/lib/mockimpl.dart

Index: lib/compiler/implementation/lib/mockimpl.dart
diff --git a/lib/compiler/implementation/lib/mockimpl.dart b/lib/compiler/implementation/lib/mockimpl.dart
index b6f18055e7e65737ee6033ffd3f0a97f538179ab..08648b963210d8818313dab8ad876dd86f21a81e 100644
--- a/lib/compiler/implementation/lib/mockimpl.dart
+++ b/lib/compiler/implementation/lib/mockimpl.dart
@@ -243,12 +243,8 @@ class DateImplementation implements Date {
     }
   }
 
-  static final int _MAX_VALUE = 8640000000000000;
-
   DateImplementation.fromEpoch(this.value, [bool isUtc = false])
-      : _isUtc = checkNull(isUtc) {
-    if (value.abs() > _MAX_VALUE) throw new IllegalArgumentException(value);
-  }
+      : _isUtc = checkNull(isUtc);
 
   bool operator ==(other) {
     if (!(other is DateImplementation)) return false;