Make WebGL objects scriptwrappable so that binding integrity checks may be applied to them.

Source/core/html/canvas/WebGLDepthTexture.cpp

Index: Source/core/html/canvas/WebGLDepthTexture.cpp
diff --git a/Source/core/html/canvas/WebGLDepthTexture.cpp b/Source/core/html/canvas/WebGLDepthTexture.cpp
index a15e91a7b4ebb915d4c259b83ed0ad178d37fb36..f9b9d84a6fcea1afcc23b50f5895eccd6c88ea87 100644
--- a/Source/core/html/canvas/WebGLDepthTexture.cpp
+++ b/Source/core/html/canvas/WebGLDepthTexture.cpp
@@ -34,6 +34,7 @@ namespace WebCore {
 WebGLDepthTexture::WebGLDepthTexture(WebGLRenderingContext* context)
     : WebGLExtension(context)
 {
+    ScriptWrappable::init(this);
     context->graphicsContext3D()->getExtensions()->ensureEnabled("GL_CHROMIUM_depth_texture");
 }