Simplify SVGElement::ParseAttribute

There's no real reason to give 'tabindex' preferential treatment (not
anymore at least.) Just let it be handled by the common fall-through
code-path and flatten the structure of the code a bit.

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I96e6c265aeb384fe1acc0b61378078bb3d06051c
Reviewed-on: https://chromium-review.googlesource.com/1179886
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584218}

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

@@ -685,10 +685,6 @@ void SVGElement::ParseAttribute(const AttributeModificationParams& params) {
     return;
   }
 
-  if (params.name == tabindexAttr) {
-    Element::ParseAttribute(params);
-  } else {
-    // standard events
   const AtomicString& event_name =
       HTMLElement::EventNameForAttributeName(params.name);
   if (!event_name.IsNull()) {
@@ -696,10 +692,10 @@ void SVGElement::ParseAttribute(const AttributeModificationParams& params) {
         event_name,
         CreateAttributeEventListener(this, params.name, params.new_value,
                                      EventParameterName()));
-    } else {
-      Element::ParseAttribute(params);
-    }
+    return;
   }
+
+  Element::ParseAttribute(params);
 }
 
 // If the attribute is not present in the map, the map will return the "empty