Namespaced attributes do not update

[AndyOGo]

Using SVG sprites with <use xlink:href="" /> will not update the icon.

The reason is that getAttributeNS and setAttributeNS DOM APIs are inconsistent in it's arguments.
E.g.: lets say 'foo:bar' ('foo' being the namespace and 'bar' the local attribute name):

• getAttributeNS only needs the localName, i.e. getAttributeNS('https://www.w3.org/1999/foo', 'bar');

  getAttributeNS(namespace, localName)
  https://www.w3.org/TR/DOM-Level-2-Core/glossary.html#dt-localname
  A local name is the local part of a qualified name. This is called the local part in Namespaces in XML [Namespaces].

• BUT setAttributeNS expects it's fully qualified name, i.e. setAttributeNS('https://www.w3.org/1999/foo', 'foo:bar');

  setAttributeNS(namespace, qualifiedName, value)
  https://www.w3.org/TR/DOM-Level-2-Core/glossary.html#dt-qualifiedname
  A qualified name is the name of an element or attribute defined as the concatenation of a local name (as defined in this specification), optionally preceded by a namespace prefix and colon character. See Qualified Names in Namespaces in XML [Namespaces].

Affected Code
https://github.com/patrick-steele-idem/morphdom/blob/master/src/morphAttrs.js#L19-L23

[AndyOGo]

same issue for nanomorph choojs/nanomorph#101

[AndyOGo]

Issue originally found in axa-ch-webhub-cloud/pattern-library#411

[AutoSponge]

SVG2 has fairly wide support now and IE11 is end-of-life. It may not be worth changing the code but encouraging folks to remove xlink:href.