message: RenderTexture stores only the bits of CreateParams which are needed
  after construction.
diff: @@ -194,14 +194,17 @@ export class PolylineEdgeArgs {
  /** A Texture for rendering */
  export abstract class RenderTexture implements IDisposable {
  - public readonly params: RenderTexture.Params;
  + public readonly key: string | undefined;
  + public readonly isGlyph: boolean;
  + public readonly isTileSection: boolean;
  - protected constructor(params: RenderTexture.Params) { this.params = params; }
  - public abstract dispose(): void;
  + protected constructor(params: RenderTexture.Params) {
  + this.key = params.key;
  + this.isGlyph = params.isGlyph;
  + this.isTileSection = params.isTileSection;
  + }
  - public get key(): string | undefined { return this.params.key; }
  - public get isGlyph(): boolean { return this.params.isGlyph; }
  - public get isTileSection(): boolean { return this.params.isTileSection; }
  + public abstract dispose(): void;
  }
  export namespace RenderTexture {
  