Fix a typo in DomQuad

We were checking for the existence of p3 then using p4.

Bug: 1150401
Change-Id: Ib7be08cd86f8962399c051b96ac837cda7934d7f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2570128
Auto-Submit: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#833217}

third_party/blink/renderer/core/geometry/dom_quad.cc

@@ -83,7 +83,7 @@ DOMQuad* DOMQuad::fromQuad(const DOMQuadInit* other) {
       other->hasP1() ? other->p1() : DOMPointInit::Create(),
       other->hasP2() ? other->p2() : DOMPointInit::Create(),
       other->hasP3() ? other->p3() : DOMPointInit::Create(),
-      other->hasP3() ? other->p4() : DOMPointInit::Create());
+      other->hasP4() ? other->p4() : DOMPointInit::Create());
 }
 
 DOMRect* DOMQuad::getBounds() {