[svg2] Make SVGLength wrap a CSSPrimitiveValue

LayoutTests/svg/dom/script-tests/SVGLength.js

Index: LayoutTests/svg/dom/script-tests/SVGLength.js
diff --git a/LayoutTests/svg/dom/script-tests/SVGLength.js b/LayoutTests/svg/dom/script-tests/SVGLength.js
index f979668593460938a9e204ed3ef0d50ef8f25adb..eb35753073f6ad7721f639373cde72c59ff4fb47 100644
--- a/LayoutTests/svg/dom/script-tests/SVGLength.js
+++ b/LayoutTests/svg/dom/script-tests/SVGLength.js
@@ -71,12 +71,14 @@ shouldBe("length.value", "2");
 shouldBe("length.valueInSpecifiedUnits", "2");
 shouldBe("length.unitType", "SVGLength.SVG_LENGTHTYPE_PX");
 
-shouldThrow("length.valueAsString = '1pX'");
-shouldBeEqualToString("length.valueAsString", "2px");
-shouldBe("length.value", "2");
-shouldBe("length.valueInSpecifiedUnits", "2");
+shouldNotThrow("length.valueAsString = '1pX'");
+shouldBeEqualToString("length.valueAsString", "1px");
+shouldBe("length.value", "1");
+shouldBe("length.valueInSpecifiedUnits", "1");
 shouldBe("length.unitType", "SVGLength.SVG_LENGTHTYPE_PX");
 
+length.valueAsString = "2px"; // reset to 2px
+
 shouldThrow("length.valueAsString = ',5 em'");
 shouldBeEqualToString("length.valueAsString", "2px");
 shouldBe("length.value", "2");