[release/6.0] Backport 'Make title prerendering not interfere with svg titles' (#44343)

* Make title prerendering not interfere with svg titles. Fixes #36380. (#37009) * Update blazor.*.js Co-authored-by: Steve Sanderson <SteveSandersonMS@users.noreply.github.com>

[release/6.0] Backport 'Make title prerendering not interfere with svg titles' (#44343)
7209d49c · Mackinnon Buck · GitHub · 538d9025 · 7209d49c · 7209d49c
--- a/src/Components/Web.JS/dist/Release/blazor.server.js
+++ b/src/Components/Web.JS/dist/Release/blazor.server.js
--- a/src/Components/Web.JS/dist/Release/blazor.webview.js
+++ b/src/Components/Web.JS/dist/Release/blazor.webview.js
--- a/src/Components/Web.JS/src/PageTitle.ts
+++ b/src/Components/Web.JS/src/PageTitle.ts
@@ -5,7 +5,8 @@ export const PageTitle = {
 };
 function getAndRemoveExistingTitle(): string | null {
-  const titleElements = document.getElementsByTagName('title');
+  // Other <title> elements may exist outside <head> (e.g., inside <svg> elements) but they aren't page titles
+  const titleElements = document.head ? document.head.getElementsByTagName('title') : [];
  if (titleElements.length === 0) {
    return null;

--- a/src/Components/test/E2ETest/ServerExecutionTests/HeadModificationPrerenderingTest.cs
+++ b/src/Components/test/E2ETest/ServerExecutionTests/HeadModificationPrerenderingTest.cs
@@ -36,6 +36,10 @@ namespace Microsoft.AspNetCore.Components.E2ETest.ServerExecutionTests
            Browser.Equal("Title 1", () => Browser.Title);
            Browser.Exists(By.Id("meta-description"));
+            // Check that unrelated <title> elements were left alone
+            Browser.Equal("This element is used to test that PageTitle prerendering doesn't interfere with non-head title elements.",
+                () => Browser.Exists(By.CssSelector("#svg-for-title-prerendering-test title")).Text);
            var titleText1 = Browser.FindElement(By.Id("title-text-1"));
            titleText1.Clear();
            titleText1.SendKeys("Updated title 1\n");

--- a/src/Components/test/testassets/TestServer/Pages/DeferredComponentContentLayout.cshtml
+++ b/src/Components/test/testassets/TestServer/Pages/DeferredComponentContentLayout.cshtml
@@ -34,5 +34,11 @@
            });
        }
    </script>
+    <svg id="svg-for-title-prerendering-test" viewBox="0 0 20 10" xmlns="http://www.w3.org/2000/svg" style="width: 1px; height: 1px;">
+        <rect x="11" y="1" width="8" height="8">
+            <title>This element is used to test that PageTitle prerendering doesn't interfere with non-head title elements.</title>
+        </rect>
+    </svg>
 </body>
 </html>