LibJS: Move throw_completion(Value) out of line

This allows us to instrument this function locally without rebuilding
1000+ files.

Userland/Libraries/LibJS/Runtime/Completion.cpp

@@ -120,4 +120,10 @@ ThrowCompletionOr<Value> await(VM& vm, Value value)
     return throw_completion(result);
 }
 
+// 6.2.3.3 ThrowCompletion ( value ), https://tc39.es/ecma262/#sec-throwcompletion
+Completion throw_completion(Value value)
+{
+    return { Completion::Type::Throw, value, {} };
+}
+
 }

Userland/Libraries/LibJS/Runtime/Completion.h

@@ -302,9 +302,6 @@ inline Completion normal_completion(Optional<Value> value)
 }
 
 // 6.2.3.3 ThrowCompletion ( value ), https://tc39.es/ecma262/#sec-throwcompletion
-inline Completion throw_completion(Value value)
-{
-    return { Completion::Type::Throw, value, {} };
-}
+Completion throw_completion(Value);
 
 }