CompiledShaderBehaviour.cs

using UnityEngine;

public class CompiledShaderBehaviour : MonoBehaviour
{
	public Shader shader;
}

CompiledShaderBehaviourEditor.cs

using UnityEngine;
using UnityEditor;

[CustomEditor(typeof(CompiledShaderBehaviour))]
public class CompiledShaderBehaviourEditor : Editor
{
	SerializedProperty shaderProperty;

	public void OnEnable ()
	{
		shaderProperty = serializedObject.FindProperty ("shader");
	}

	public override void OnInspectorGUI ()
	{
		serializedObject.Update ();

		EditorGUILayout.PropertyField (shaderProperty);

		Shader shader = shaderProperty.objectReferenceValue as Shader;
		if (shader)
		{
			string compiledShaderString = (new SerializedObject(shader)).FindProperty("m_Script").stringValue;

			EditorGUILayout.TextArea (compiledShaderString);
		}

		serializedObject.ApplyModifiedProperties ();
	}
}