[webcrypto] Fix TODO regarding asynchronous completion of crypto operations.

Source/modules/crypto/SubtleCrypto.cpp

Index: Source/modules/crypto/SubtleCrypto.cpp
diff --git a/Source/modules/crypto/SubtleCrypto.cpp b/Source/modules/crypto/SubtleCrypto.cpp
index e92c1dbf8373523931adec6be5ab7af48342ca54..ef175c3eccb18a037c1f336d64242fcb94e3a1d8 100644
--- a/Source/modules/crypto/SubtleCrypto.cpp
+++ b/Source/modules/crypto/SubtleCrypto.cpp
@@ -44,9 +44,6 @@
 
 namespace WebCore {
 
-// FIXME: asynchronous completion of CryptoResult. Need to re-enter the
-//        v8::Context before trying to fulfill the promise, and enable test.
-
 namespace {
 
 ScriptPromise startCryptoOperation(const Dictionary& rawAlgorithm, Key* key, AlgorithmOperation operationType, ArrayBufferView* signature, ArrayBufferView* dataBuffer, ExceptionState& exceptionState)