CSSURLImageValue should validate URLs

As per the spec[1],
Constructing CSSURLImageValue should throw an error,
if the URL is invalid.
[1] https://drafts.css-houdini.org/css-typed-om-1/#dom-cssurlimagevalue-cssurlimagevalue

Bug: 791434
Change-Id: I06ae5dad378ca91ce827f64ff56498a06c9963af
Reviewed-on: https://chromium-review.googlesource.com/805635Reviewed-by: Darren Shen <shend@chromium.org>
Commit-Queue: Shanmuga Pandi <shanmuga.m@samsung.com>
Cr-Commit-Position: refs/heads/master@{#521574}

third_party/WebKit/LayoutTests/typedcssom/stylevalue-subclasses/cssUrlImageValue-expected.txt

 This is a testharness.js-based test.
-FAIL Constructing a CSSURLImageValue with an invalid URL throws a TypeError assert_throws: function "() => new CSSURLImageValue('not url')" did not throw
+PASS Constructing a CSSURLImageValue with an invalid URL throws a TypeError
 PASS Constructing a CSSURLImageValue with a valid URL puts it in an unloaded state
 PASS CSSURLImageValue.url is readonly
 PASS Loading a CSSURLImageValue from a URL sets its state to loaded

third_party/WebKit/LayoutTests/typedcssom/stylevalue-subclasses/cssUrlImageValue.html

@@ -26,7 +26,7 @@ const gBase64TestUrl = 'data:image/gif;base64,R0lGODlhAQABAAAAACwAAAAAAQABAAA=';
 const gBadTestUrl = document.location.href;
 
 test(() => {
-  assert_throws(new TypeError(), () => new CSSURLImageValue('not url'));
+  assert_throws(new TypeError(), () => new CSSURLImageValue("file://:This is invalid url"));
 }, 'Constructing a CSSURLImageValue with an invalid URL throws a TypeError');
 
 test(() => {

third_party/WebKit/Source/core/css/cssom/CSSURLImageValue.h

@@ -16,13 +16,19 @@ class CORE_EXPORT CSSURLImageValue final : public CSSStyleImageValue {
 
  public:
   static CSSURLImageValue* Create(ScriptState* script_state,
-                                  const AtomicString& url) {
+                                  const AtomicString& url,
+                                  ExceptionState& exception_state) {
     const auto* execution_context = ExecutionContext::From(script_state);
     DCHECK(execution_context);
+    KURL parsed_url = execution_context->CompleteURL(url);
+    if (!parsed_url.IsValid()) {
+      exception_state.ThrowTypeError("Failed to parse URL from " + url);
+      return nullptr;
+    }
     // Use absolute URL for CSSImageValue but keep relative URL for
     // getter and serialization.
-    return new CSSURLImageValue(CSSImageValue::Create(
-        url, execution_context->CompleteURL(url), Referrer()));
+    return new CSSURLImageValue(
+        CSSImageValue::Create(url, parsed_url, Referrer()));
   }
   static CSSURLImageValue* Create(const CSSImageValue* image_value) {
     return new CSSURLImageValue(image_value);

third_party/WebKit/Source/core/css/cssom/CSSURLImageValue.idl

@@ -8,6 +8,7 @@
     Constructor(USVString url),
     ConstructorCallWith=ScriptState,
     Exposed=(Window,PaintWorklet),
+    RaisesException=Constructor,
     RuntimeEnabled=CSSTypedOM
 ] interface CSSURLImageValue : CSSImageValue {
     readonly attribute USVString url;