Fix the crash of compressedTexImage3D for the WebGL2 conformance test page.

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp b/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp
index e8d9ee846d1ac3f0b0e95e7e5915a68a22b34ce5..096d663cb8163e265c158d81e939dc5bba171805 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp
@@ -929,6 +929,11 @@ void WebGL2RenderingContextBase::compressedTexImage3D(GLenum target, GLint level
     if (!tex)
         return;
 
+    if (internalformat != tex->getInternalFormat(target, level)) {

[qiankun, 2015/11/23 09:44:27]

CompressedTexImage3D is used to specify a three-dimensional texture image in a
compressed format. So no previously defined texture. This check should always
fail. Also ES3 doesn't have such limitation on internalformat matching. I think
you should do level validation here according your first CL.

+        synthesizeGLError(GL_INVALID_OPERATION, "compressedTexImage3D", "format does not match texture format");
+        return;
+    }
+
     if (tex->isImmutable()) {
         synthesizeGLError(GL_INVALID_OPERATION, "compressedTexImage3D", "attempted to modify immutable texture");
         return;