Bug 1443316 - part 3 - make cache entry request checking more readable; r=ckerschb

What we're really doing in CacheEntry::CheckRequest is checking:

a) Whether the method is contained in our allowed methods; and
b) Whether all of the headers are contained in our allowed headers.

nsTArray lets us check directly for containing elements, so let's use
that facility rather than rolling our own.

netwerk/protocol/http/nsCORSListenerProxy.cpp

@@ -210,25 +210,26 @@ nsPreflightCache::CacheEntry::CheckRequest(const nsCString& aMethod,
   PurgeExpired(TimeStamp::NowLoRes());
 
   if (!aMethod.EqualsLiteral("GET") && !aMethod.EqualsLiteral("POST")) {
-    uint32_t i;
-    for (i = 0; i < mMethods.Length(); ++i) {
-      if (aMethod.Equals(mMethods[i].token))
-        break;
-    }
-    if (i == mMethods.Length()) {
+    struct CheckToken {
+      bool Equals(const TokenTime& e, const nsCString& method) const {
+        return e.token.Equals(method);
+      }
+    };
+
+    if (!mMethods.Contains(aMethod, CheckToken())) {
       return false;
     }
   }
 
-  for (uint32_t i = 0; i < aHeaders.Length(); ++i) {
-    uint32_t j;
-    const auto& comparator = nsCaseInsensitiveCStringComparator();
-    for (j = 0; j < mHeaders.Length(); ++j) {
-      if (aHeaders[i].Equals(mHeaders[j].token, comparator)) {
-        break;
-      }
+  const struct CheckHeaderToken {
+    bool Equals(const TokenTime& e, const nsCString& header) const {
+      return e.token.Equals(header, comparator);
     }
-    if (j == mHeaders.Length()) {
+
+    const nsCaseInsensitiveCStringComparator comparator;
+  } checker;
+  for (uint32_t i = 0; i < aHeaders.Length(); ++i) {
+    if (!mHeaders.Contains(aHeaders[i], checker)) {
       return false;
     }
   }