File constructor understands lastModified.

LayoutTests/fast/files/blob-constructor.html

Index: LayoutTests/fast/files/blob-constructor.html
diff --git a/LayoutTests/fast/files/blob-constructor.html b/LayoutTests/fast/files/blob-constructor.html
index f5c125f3b00fe0ed983f02a9416315b05d7e0453..8d6023d91337be2de29dc2022865622328046922 100644
--- a/LayoutTests/fast/files/blob-constructor.html
+++ b/LayoutTests/fast/files/blob-constructor.html
@@ -61,11 +61,16 @@ shouldBeTrue("(new Blob([], [])) instanceof window.Blob");
 shouldBeTrue("(new Blob([], /abc/)) instanceof window.Blob");
 shouldBeTrue("(new Blob([], function () {})) instanceof window.Blob");
 
-// Test that the type/size is correctly added to the Blob
+// Test that the type/size is correctly added to the Blob.
 shouldBe("(new Blob([], {type:'text/html'})).type", "'text/html'");
 shouldBe("(new Blob([], {type:'text/html'})).size", "0");
 shouldBe("(new Blob([], {type:'text/plain;charset=UTF-8'})).type", "'text/plain;charset=utf-8'");
 
+// Test that the File-specific lastModified is not set by the Blob constructor.
+shouldBe("(new Blob([])).lastModified", "undefined");
+shouldBe("(new Blob([], {})).lastModified", "undefined");
+shouldBe("(new Blob([], {lastModified: new Date()})).lastModified", "undefined");
+
 // Test the number of expected arguments in the Blob constructor.
 shouldBe("window.Blob.length", "0");