Split "Online" and "Offline" AudioContext processing

Source/modules/webaudio/AudioParamTimeline.h

Index: Source/modules/webaudio/AudioParamTimeline.h
diff --git a/Source/modules/webaudio/AudioParamTimeline.h b/Source/modules/webaudio/AudioParamTimeline.h
index 676d8217fb1ccdefbfb05367f3a17e8777fded3d..38c05b4a646adf385f6ea864b473c46902621f8e 100644
--- a/Source/modules/webaudio/AudioParamTimeline.h
+++ b/Source/modules/webaudio/AudioParamTimeline.h
@@ -30,7 +30,7 @@
 #define AudioParamTimeline_h
 
 #include "core/dom/DOMTypedArray.h"
-#include "modules/webaudio/AudioContext.h"
+#include "modules/webaudio/AbstractAudioContext.h"
 #include "wtf/Forward.h"
 #include "wtf/Threading.h"
 #include "wtf/Vector.h"
@@ -52,7 +52,7 @@ public:
 
     // hasValue is set to true if a valid timeline value is returned.
     // otherwise defaultValue is returned.
-    float valueForContextTime(AudioContext*, float defaultValue, bool& hasValue);
+    float valueForContextTime(AbstractAudioContext*, float defaultValue, bool& hasValue);
 
     // Given the time range, calculates parameter values into the values buffer
     // and returns the last parameter value calculated for "values" or the defaultValue if none were calculated.