The default for x1, y1 and y2 is 0% for LinearGradient

Source/core/svg/SVGLinearGradientElement.cpp

Index: Source/core/svg/SVGLinearGradientElement.cpp
diff --git a/Source/core/svg/SVGLinearGradientElement.cpp b/Source/core/svg/SVGLinearGradientElement.cpp
index ec7a890eef226f4b93f11e01ed7e8303236f8c75..8fb442732261a7e480b4ab700fc4b1f19359b5bf 100644
--- a/Source/core/svg/SVGLinearGradientElement.cpp
+++ b/Source/core/svg/SVGLinearGradientElement.cpp
@@ -37,6 +37,12 @@ inline SVGLinearGradientElement::SVGLinearGradientElement(Document& document)
     , m_x2(SVGAnimatedLength::create(this, SVGNames::x2Attr, SVGLength::create(SVGLengthMode::Width), AllowNegativeLengths))
     , m_y2(SVGAnimatedLength::create(this, SVGNames::y2Attr, SVGLength::create(SVGLengthMode::Height), AllowNegativeLengths))
 {
+
+    // Spec: If the x1|y1|y2 attribute is not specified, the effect is as if a value of "0%" were specified.
+    m_x1->setDefaultValueAsString("0%");
+    m_y1->setDefaultValueAsString("0%");
+    m_y2->setDefaultValueAsString("0%");
+
     // Spec: If the x2 attribute is not specified, the effect is as if a value of "100%" were specified.
     m_x2->setDefaultValueAsString("100%");