Remove dead code in SVGResources::RemoveClientFromCache

This method is never called for a LayoutObject which has a "linked"
resource (<pattern>), so remove the handling of |linked_resource_|.

Change-Id: I8c57804ecb58f4b7e286e427f0b7de84909286b8
Reviewed-on: https://chromium-review.googlesource.com/1243807Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#594041}

third_party/blink/renderer/core/layout/svg/svg_resources.cc

@@ -291,15 +291,8 @@ InvalidationModeMask SVGResources::RemoveClientFromCache(
   if (!HasResourceData())
     return 0;
 
-  if (linked_resource_) {
-    DCHECK(!clipper_filter_masker_data_);
-    DCHECK(!marker_data_);
-    DCHECK(!fill_stroke_data_);
-    linked_resource_->RemoveClientFromCache(client);
-    // The only linked resources are gradients and patterns, i.e
-    // always a paint server.
-    return SVGResourceClient::kPaintInvalidation;
-  }
+  // We never call this method for the elements where this would be non-null.
+  DCHECK(!linked_resource_);
 
   InvalidationModeMask invalidation_flags =
       RemoveClientFromCacheAffectingObjectBounds(client);