Add support for the object-fit CSS property.

LayoutTests/fast/css/script-tests/parsing-object-fit.js

+description("This tests checks that all of the input values for -webkit-object-fit parse correctly.");
+
+function test(value)
+{
+    var div = document.createElement("div");
+    div.setAttribute("style", value);
+    document.body.appendChild(div);
+
+    var result = div.style.getPropertyValue("object-fit");
+    document.body.removeChild(div);
+    return result;
+}
+
+function testComputedStyle(value)
+{
+    var div = document.createElement("div");
+    div.setAttribute("style", value);
+    document.body.appendChild(div);
+
+    var result = window.getComputedStyle(div).objectFit;
+    document.body.removeChild(div);
+    return result;
+}
+
+shouldBe('testComputedStyle(";")', '"fill"');
+shouldBe('test("object-fit: inherit;")', '"inherit"');
+shouldBe('test("object-fit: initial;")', '"initial"');
+shouldBe('test("object-fit: fill;")', '"fill"');
+shouldBe('test("object-fit: contain;")', '"contain"');
+shouldBe('test("object-fit: cover;")', '"cover"');
+shouldBe('test("object-fit: none;")', '"none"');
+shouldBe('test("object-fit: scale-down;")', '"scale-down"');
+
+shouldBeNull('test("object-fit: fill contain;")');
+shouldBeNull('test("object-fit: bananas;")');
+shouldBeNull('test("object-fit: 23px;")');
+shouldBeNull('test("object-fit: 20%;")');
+
+var successfullyParsed = true;