fix(material/icon): keep FuncIRI references on current origin (#33812)

Paths beginning with two slashes were interpreted as protocol-relative URLs when MatIcon rewrote same-document SVG references. Prefix those paths with a dot segment so they resolve on the current origin while retaining the current document path.

Author: moamenmahmod

src/material/icon/icon.spec.ts

@@ -1012,6 +1012,32 @@ describe('MatIcon', () => {
       expect(circle.getAttribute('filter')).toMatch(/^url\(['"]?\/\$fake-path#blur['"]?\)$/);
     });
 
+    it('should not create protocol-relative `url()` references', () => {
+      fakePath = '////$fake-host/path?x=1';
+      iconRegistry.addSvgIconLiteral(
+        'fido',
+        trustHtml(`
+        <svg>
+          <filter id="blur">
+            <feGaussianBlur in="SourceGraphic" stdDeviation="5" />
+          </filter>
+
+          <circle cx="170" cy="60" r="50" fill="green" filter="url('#blur')" />
+        </svg>
+      `),
+      );
+
+      const fixture = TestBed.createComponent(IconFromSvgName);
+      fixture.componentInstance.iconName = 'fido';
+      fixture.changeDetectorRef.markForCheck();
+      fixture.detectChanges();
+      const circle = fixture.nativeElement.querySelector('mat-icon svg circle');
+
+      expect(circle.getAttribute('filter')).toMatch(
+        /^url\(['"]?\/\.\/\/\/\/\$fake-host\/path\?x=1#blur['"]?\)$/,
+      );
+    });
+
     it('should use latest path when prefixing the `url()` references', () => {
       iconRegistry.addSvgIconLiteral(
         'fido',

src/material/icon/icon.ts

@@ -404,11 +404,15 @@ export class MatIcon implements OnInit, AfterViewChecked, OnDestroy {
    */
   private _prependPathToReferences(path: string) {
     const elements = this._elementsWithExternalReferences;
+    // A path starting with `//` would otherwise be interpreted as a protocol-relative URL.
+    // Prefix it with a dot segment so it stays on the current origin without changing the resolved
+    // path.
+    const normalizedPath = path.startsWith('//') ? `/.${path}` : path;
 
     if (elements) {
       elements.forEach((attrs, element) => {
         attrs.forEach(attr => {
-          element.setAttribute(attr.name, `url('${path}#${attr.value}')`);
+          element.setAttribute(attr.name, `url('${normalizedPath}#${attr.value}')`);
         });
       });
     }