Remove using directives ("using namespace x") from blink/renderer/core/svg/.

Bug: 82078
Change-Id: I13e7bd190e628d85f3bacbaca5e33108f94337f8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1866266
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#706858}

third_party/blink/renderer/core/svg/svg_a_element.cc

@@ -48,8 +48,6 @@
 
 namespace blink {
 
-using namespace html_names;
-
 SVGAElement::SVGAElement(Document& document)
     : SVGGraphicsElement(svg_names::kATag, document),
       SVGURIReference(this),
@@ -183,7 +181,7 @@ bool SVGAElement::ShouldHaveFocusAppearance() const {
 }
 
 bool SVGAElement::IsURLAttribute(const Attribute& attribute) const {
-  return attribute.GetName().LocalName() == kHrefAttr ||
+  return attribute.GetName().LocalName() == html_names::kHrefAttr ||
          SVGGraphicsElement::IsURLAttribute(attribute);
 }