File constructor understands lastModified.

LayoutTests/fast/files/file-constructor.html

Index: LayoutTests/fast/files/file-constructor.html
diff --git a/LayoutTests/fast/files/file-constructor.html b/LayoutTests/fast/files/file-constructor.html
index f615864f75e496d559deab8828f0874b669cf0b7..5fe99e6d819851e68a59cc433948890f0f646524 100644
--- a/LayoutTests/fast/files/file-constructor.html
+++ b/LayoutTests/fast/files/file-constructor.html
@@ -87,6 +87,23 @@ shouldBe("(new File([], 'world.html', {type:'text/html'})).type", "'text/html'")
 shouldBe("(new File([], 'world.html', {type:'text/html'})).size", "0");
 shouldBe("(new File([], 'world.html', {type:'text/plain;charset=UTF-8'})).type", "'text/plain;charset=utf-8'");
 
+// Test that the lastModified is correctly added to the File.
+var aDate = new Date(441532800000);
+shouldBe("(new File([], 'world.html', {lastModified: 441532800000})).lastModified", "441532800000");
+// Unless specified, lastModified should default to now.
+var startTime = Date.now();
+var fileTime = (new File([], 'world.html')).lastModified;
+var endTime = Date.now();
+// FIXME: these checks will fail if time goes backwards, e.g. NTP updates. We should have a generic bullet-proof method for comparing against Date.now(). http://crbug.com/320686
+shouldBeTrue("startTime <= fileTime");
+shouldBeTrue("fileTime <= endTime");
+// Test that Date instances are implicitly converted to numbers.
+shouldBe("(new File([], 'world.html', {lastModified: new Date(441532800000)})).lastModified", "441532800000");
+
+// Test the deprecated attribute lastModifiedDate.
+shouldBeTrue("(new File([], 'world.html', {lastModified: 441532800000})).lastModifiedDate instanceof Date");
+shouldBe("(new File([], 'world.html', {lastModified: 441532800000})).lastModifiedDate.valueOf()", "441532800000");
+
 // Test the number of expected arguments in the File constructor.
 shouldBe("window.File.length", "2");