SVG doesn't recognize rem units

Source/core/svg/SVGLengthContext.h

Index: Source/core/svg/SVGLengthContext.h
diff --git a/Source/core/svg/SVGLengthContext.h b/Source/core/svg/SVGLengthContext.h
index 43bc3e6cf44aaa0bcd7a52b2e96d7f59b48e645d..3e2ba449e39ff51955464b4e114178830188c6b6 100644
--- a/Source/core/svg/SVGLengthContext.h
+++ b/Source/core/svg/SVGLengthContext.h
@@ -42,7 +42,8 @@ enum SVGLengthType {
     LengthTypeMM,
     LengthTypeIN,
     LengthTypePT,
-    LengthTypePC
+    LengthTypePC,
+    LengthTypeREMS
 };
 
 enum class SVGLengthMode {
@@ -85,6 +86,9 @@ private:
     float convertValueFromUserUnitsToEXS(float value) const;
     float convertValueFromEXSToUserUnits(float value) const;
 
+    float convertValueFromUserUnitsToREMS(float value) const;
+    float convertValueFromREMSToUserUnits(float value) const;
+
     RawPtrWillBeMember<const SVGElement> m_context;
 };