move KeyUsageAllows to more logical place(part1)

Source/platform/exported/WebCryptoKey.cpp

Index: Source/platform/exported/WebCryptoKey.cpp
diff --git a/Source/platform/exported/WebCryptoKey.cpp b/Source/platform/exported/WebCryptoKey.cpp
index 28f95b433ba736e228d7ebb9887f1a98757f148f..74d0ca75ac1cc3a277babe6cc17536fa7a88bd37 100644
--- a/Source/platform/exported/WebCryptoKey.cpp
+++ b/Source/platform/exported/WebCryptoKey.cpp
@@ -105,6 +105,11 @@ bool WebCryptoKey::isNull() const
     return m_private.isNull();
 }
 
+bool WebCryptoKey::keyUsageAllows(const blink::WebCryptoKeyUsage usage) const
+{
+    return ((m_private->usages & usage) != 0);
+}
+
 void WebCryptoKey::assign(const WebCryptoKey& other)
 {
     m_private = other.m_private;