Use HashMap::Take(...) in Document::RemoveComputedStyleMapItem

at(<key>)+erase(<key>) is two hash computations, which can be replaced
with Take(<key>).

Change-Id: I0300052c629177ffb5317a8b58c222f32b0c1e38
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1903201Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#713452}

third_party/blink/renderer/core/dom/document.cc

@@ -8233,10 +8233,7 @@ void Document::AddComputedStyleMapItem(
 
 StylePropertyMapReadOnly* Document::RemoveComputedStyleMapItem(
     Element* element) {
-  StylePropertyMapReadOnly* computed_style =
-      element_computed_style_map_.at(element);
-  element_computed_style_map_.erase(element);
-  return computed_style;
+  return element_computed_style_map_.Take(element);
 }
 
 void Document::Trace(Visitor* visitor) {