Simplify DocumentStyleEnvironmentVariables::GenerateHashFromName

Use the StringHasher::ComputeHash() helper.

Change-Id: Ic43c19467a9d15f1b82c4ac586ebe7b80f937c60
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1762220Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#688709}

third_party/blink/renderer/core/css/document_style_environment_variables.cc

@@ -15,17 +15,9 @@ namespace blink {
 // static
 unsigned DocumentStyleEnvironmentVariables::GenerateHashFromName(
     const AtomicString& name) {
-  StringHasher hasher;
-
-  if (name.Is8Bit()) {
-    String name_str = String(name);
-    name_str.Ensure16Bit();
-    hasher.AddCharacters(name_str.Characters16(), name_str.length());
-  } else {
-    hasher.AddCharacters(name.Characters16(), name.length());
-  }
-
-  return hasher.GetHash();
+  if (name.Is8Bit())
+    return StringHasher::ComputeHash(name.Characters8(), name.length());
+  return StringHasher::ComputeHash(name.Characters16(), name.length());
 }
 
 // static