Make fragment-only URLs always be document-local references

third_party/WebKit/Source/core/svg/SVGURIReference.h

Index: third_party/WebKit/Source/core/svg/SVGURIReference.h
diff --git a/third_party/WebKit/Source/core/svg/SVGURIReference.h b/third_party/WebKit/Source/core/svg/SVGURIReference.h
index 97248ec0c9c9b00a9e88cd16a08ff514fdc8050e..4f2b706858d99fe0e38a627a800034ebac8bb33b 100644
--- a/third_party/WebKit/Source/core/svg/SVGURIReference.h
+++ b/third_party/WebKit/Source/core/svg/SVGURIReference.h
@@ -74,6 +74,24 @@ private:
     Member<SVGAnimatedHref> m_href;
 };
 
+// Helper class used to resolve fragment references. Handles the 'local url
+// flag' per https://drafts.csswg.org/css-values/#local-urls .

[pdr., 2016/07/22 19:18:28]

Can you add a test (maybe like
http/tests/misc/input-image-fallback-content-crash.html) where the base href +
fragment is valid but we still choose the local object over the external one?

[fs, 2016/07/22 21:15:03]

Done.

+class SVGURLReferenceResolver {

[pdr., 2016/07/22 19:18:28]

I'm wondering if this belongs in SVG or somewhere more generic. The spec doesn't
specifically require that this only applies to SVG even though most cases are.
Could HTMLMapElement / HTMLImageElement::isServerMap also use this?

[pdr., 2016/07/22 20:02:31]

Answering my own question, image maps don't use the url syntax. My greps aren't
hitting any non-svg examples in our tests either. I suspect this is fine as
SVGURLReferenceResolver.

[fs, 2016/07/22 21:15:02]

The spec is for CSS values, and subsequently referenced by SVG. I've made
provisions for adding a mechanism for this to CSSURIValue, with roughly the same
ergonomics. In the end I decided that it didn't fit very well together with this
CL. I've moved it to another CL (one about resolving against CSS stylesheets
when needed.) 

Usemap is specced by HTML [1][2], so we should probably not touch them unless
otherwise indicated.

[1]
https://html.spec.whatwg.org/multipage/infrastructure.html#rules-for-parsing-...
[2]
https://html.spec.whatwg.org/multipage/embedded-content.html#attr-hyperlink-u...

+    STACK_ALLOCATED();
+public:
+    SVGURLReferenceResolver(const String& urlString, const Document&);
+
+    bool isLocal() const;

[pdr., 2016/07/22 19:18:28]

Can you update isExternalURIReference to use this cool new technology? I think
it's doing the same logic.

[fs, 2016/07/22 21:15:02]

Yes, that's a good point. isExternalURIReference only had one user
(SVGUseElement), and that one could trivially be replaced with a simpler check,
so I dropped the helper method.

+    KURL absoluteUrl() const;
+    AtomicString fragmentIdentifier() const;
+
+private:
+    const String& m_relativeUrl;
+    Member<const Document> m_document;
+    mutable KURL m_absoluteUrl;
+    bool m_isLocal;
+};
+
 } // namespace blink
 
 #endif // SVGURIReference_h