Split Dictionary's get and convert into DictionaryHelper.

Source/modules/mediastream/RTCIceCandidate.cpp

Index: Source/modules/mediastream/RTCIceCandidate.cpp
diff --git a/Source/modules/mediastream/RTCIceCandidate.cpp b/Source/modules/mediastream/RTCIceCandidate.cpp
index 7e479c31a4525ddd1ee1d5f9a915779a373dfc1c..8e4ce57571bf66bd11e0d660f2ea019f19d87094 100644
--- a/Source/modules/mediastream/RTCIceCandidate.cpp
+++ b/Source/modules/mediastream/RTCIceCandidate.cpp
@@ -41,17 +41,17 @@ namespace WebCore {
 RTCIceCandidate* RTCIceCandidate::create(const Dictionary& dictionary, ExceptionState& exceptionState)
 {
     String candidate;
-    bool ok = dictionary.get("candidate", candidate);
+    bool ok = DictionaryHelper::get(dictionary, "candidate", candidate);
     if (!ok || !candidate.length()) {
         exceptionState.throwDOMException(TypeMismatchError, ExceptionMessages::incorrectPropertyType("candidate", "is not a string, or is empty."));
         return nullptr;
     }
 
     String sdpMid;
-    dictionary.get("sdpMid", sdpMid);
+    DictionaryHelper::get(dictionary, "sdpMid", sdpMid);
 
     unsigned short sdpMLineIndex = 0;
-    dictionary.get("sdpMLineIndex", sdpMLineIndex);
+    DictionaryHelper::get(dictionary, "sdpMLineIndex", sdpMLineIndex);
 
     return new RTCIceCandidate(blink::WebRTCICECandidate(candidate, sdpMid, sdpMLineIndex));
 }