Eliminate deprecated Int32/Int64.fromInt() constructors

pkg/fixnum/lib/src/int64.dart

Index: pkg/fixnum/lib/src/int64.dart
diff --git a/pkg/fixnum/lib/src/int64.dart b/pkg/fixnum/lib/src/int64.dart
index 192b11f68a89ab0aad10a0b013b4baeca0dbe39f..78019205c9c965be13fb2289a535c397f507f10c 100644
--- a/pkg/fixnum/lib/src/int64.dart
+++ b/pkg/fixnum/lib/src/int64.dart
@@ -148,12 +148,6 @@ class Int64 implements IntX {
     return new Int64._bits(v0, v1, v2);
   }
 
-  /**
-   * Constructs an [Int64] with a given [int] value.
-   */
-  @deprecated
-  factory Int64.fromInt(int value) => new Int64(value);
-
   factory Int64.fromBytes(List<int> bytes) {
     int top = bytes[7] & 0xff;
     top <<= 8;