moving toJSON implementation to the BaseContext

Tone/core/context/BaseContext.ts

@@ -149,7 +149,14 @@ export abstract class BaseContext
 
 	abstract immediate(): Seconds;
 
-	abstract toJSON(): Record<string, any>;
+	/*
+	 * This is a placeholder so that JSON.stringify does not throw an error
+	 * This matches what JSON.stringify(audioContext) returns on a native
+	 * audioContext instance.
+	 */
+	toJSON(): Record<string, any> {
+		return {};
+	}
 
 	readonly isOffline: boolean = false;
 }

Tone/core/context/Context.ts

@@ -625,13 +625,4 @@ export class Context extends BaseContext {
 		intervalFn();
 		return id;
 	}
-
-	/*
-	 * This is a placeholder so that JSON.stringify does not throw an error
-	 * This matches what JSON.stringify(audioContext) returns on a native
-	 * audioContext instance.
-	 */
-	toJSON() {
-		return {};
-	}
 }

Tone/core/context/DummyContext.ts

@@ -197,9 +197,5 @@ export class DummyContext extends BaseContext {
 		return 0;
 	}
 
-	toJSON() {
-		return {};
-	}
-
 	readonly isOffline: boolean = false;
 }