Fixed expando-loss.html test.

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

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 855 matching lines @@
 
 } // namespace anonymous
 
 WebGLRenderingContextBase::WebGLRenderingContextBase(HTMLCanvasElement* passedCanvas, PassOwnPtr<WebGraphicsContext3D> context, const WebGLContextAttributes& requestedAttributes)
     : CanvasRenderingContext(passedCanvas)
     , m_contextLostMode(NotLostContext)
     , m_autoRecoveryMethod(Manual)
     , m_dispatchContextLostEventTimer(this, &WebGLRenderingContextBase::dispatchContextLostEvent)
     , m_restoreAllowed(false)
     , m_restoreTimer(this, &WebGLRenderingContextBase::maybeRestoreContext)
+    , m_preservedDefaultVAOObjectWrapper(false)
     , m_generatedImageCache(4)
     , m_requestedAttributes(requestedAttributes)
     , m_synthesizedErrorsToConsole(true)
     , m_numGLErrorsToConsoleAllowed(maxGLErrorsAllowedToConsole)
     , m_multisamplingAllowed(false)
     , m_multisamplingObserverRegistered(false)
     , m_onePlusMaxNonDefaultTextureUnit(0)
     , m_isWebGL2FormatsTypesAdded(false)
     , m_isOESTextureFloatFormatsTypesAdded(false)
     , m_isOESTextureHalfFloatFormatsTypesAdded(false)
@@ skipping 100 matching lines @@
     m_backDrawBuffer = GL_BACK;
 
     m_readBufferOfDefaultFramebuffer = GL_BACK;
 
     if (isWebGL2OrHigher()) {
         m_defaultVertexArrayObject = WebGLVertexArrayObject::create(this, WebGLVertexArrayObjectBase::VaoTypeDefault);
     } else {
         m_defaultVertexArrayObject = WebGLVertexArrayObjectOES::create(this, WebGLVertexArrayObjectBase::VaoTypeDefault);
     }
     addContextObject(m_defaultVertexArrayObject.get());
+    // We can't preserve this object's wrapper yet since there's no ScriptState available.
+    m_preservedDefaultVAOObjectWrapper = false;
     m_boundVertexArrayObject = m_defaultVertexArrayObject;
 
     m_vertexAttribValue.resize(m_maxVertexAttribs);
 
     createFallbackBlackTextures1x1();
 
     webContext()->viewport(0, 0, drawingBufferWidth(), drawingBufferHeight());
     webContext()->scissor(0, 0, drawingBufferWidth(), drawingBufferHeight());
 
     m_contextLostCallbackAdapter = WebGLRenderingContextLostCallback::create(this);
@@ skipping 351 matching lines @@
         synthesizeGLError(GL_INVALID_ENUM, "activeTexture", "texture unit out of range");
         return;
     }
     m_activeTextureUnit = texture - GL_TEXTURE0;
     webContext()->activeTexture(texture);
 
     drawingBuffer()->setActiveTextureUnit(texture);
 
 }
 
-void WebGLRenderingContextBase::attachShader(WebGLProgram* program, WebGLShader* shader)
+void WebGLRenderingContextBase::attachShader(ScriptState* scriptState, WebGLProgram* program, WebGLShader* shader)
 {
     if (isContextLost() || !validateWebGLObject("attachShader", program) || !validateWebGLObject("attachShader", shader))
         return;
     if (!program->attachShader(shader)) {
         synthesizeGLError(GL_INVALID_OPERATION, "attachShader", "shader attachment already has shader");
         return;
     }
     webContext()->attachShader(objectOrZero(program), objectOrZero(shader));
     shader->onAttached();
+    preserveObjectWrapper(scriptState, program, "shader", shader->type(), shader);
 }
 
 void WebGLRenderingContextBase::bindAttribLocation(WebGLProgram* program, GLuint index, const String& name)
 {
     if (isContextLost() || !validateWebGLObject("bindAttribLocation", program))
         return;
     if (!validateLocationLength("bindAttribLocation", name))
         return;
     if (!validateString("bindAttribLocation", name))
         return;
@@ skipping 43 matching lines @@
     default:
         ASSERT_NOT_REACHED();
         return false;
     }
 
     if (buffer && !buffer->getInitialTarget())
         buffer->setInitialTarget(target);
     return true;
 }
 
-void WebGLRenderingContextBase::bindBuffer(GLenum target, WebGLBuffer* buffer)
+void WebGLRenderingContextBase::bindBuffer(ScriptState* scriptState, GLenum target, WebGLBuffer* buffer)
 {
     bool deleted;
     if (!checkObjectToBeBound("bindBuffer", buffer, deleted))
         return;
     if (deleted)
         buffer = 0;
     if (!validateAndUpdateBufferBindTarget("bindBuffer", target, buffer))
         return;
 
     webContext()->bindBuffer(target, objectOrZero(buffer));
+    preserveObjectWrapper(scriptState, this, "buffer", target, buffer);
+    maybePreserveDefaultVAOObjectWrapper(scriptState);
 }
 
-void WebGLRenderingContextBase::bindFramebuffer(GLenum target, WebGLFramebuffer* buffer)
+void WebGLRenderingContextBase::bindFramebuffer(ScriptState* scriptState, GLenum target, WebGLFramebuffer* buffer)
 {
     bool deleted;
     if (!checkObjectToBeBound("bindFramebuffer", buffer, deleted))
         return;
 
     if (deleted)
         buffer = 0;
 
     if (target != GL_FRAMEBUFFER) {
         synthesizeGLError(GL_INVALID_ENUM, "bindFramebuffer", "invalid target");
         return;
     }
 
     setFramebuffer(target, buffer);
+    if (scriptState)
+        preserveObjectWrapper(scriptState, this, "framebuffer", 0, buffer);
 }
 
-void WebGLRenderingContextBase::bindRenderbuffer(GLenum target, WebGLRenderbuffer* renderBuffer)
+void WebGLRenderingContextBase::bindRenderbuffer(ScriptState* scriptState, GLenum target, WebGLRenderbuffer* renderBuffer)
 {
     bool deleted;
     if (!checkObjectToBeBound("bindRenderbuffer", renderBuffer, deleted))
         return;
     if (deleted)
         renderBuffer = 0;
     if (target != GL_RENDERBUFFER) {
         synthesizeGLError(GL_INVALID_ENUM, "bindRenderbuffer", "invalid target");
         return;
     }
     m_renderbufferBinding = renderBuffer;
     webContext()->bindRenderbuffer(target, objectOrZero(renderBuffer));
+    preserveObjectWrapper(scriptState, this, "renderbuffer", 0, renderBuffer);
     if (renderBuffer)
         renderBuffer->setHasEverBeenBound();
 }
 
-void WebGLRenderingContextBase::bindTexture(GLenum target, WebGLTexture* texture)
+void WebGLRenderingContextBase::bindTexture(ScriptState* scriptState, GLenum target, WebGLTexture* texture)
 {
     bool deleted;
     if (!checkObjectToBeBound("bindTexture", texture, deleted))
         return;
     if (deleted)
         texture = 0;
     if (texture && texture->getTarget() && texture->getTarget() != target) {
         synthesizeGLError(GL_INVALID_OPERATION, "bindTexture", "textures can not be used with multiple targets");
         return;
     }
+
+    const char* bindingPointName = nullptr;
     if (target == GL_TEXTURE_2D) {
         m_textureUnits[m_activeTextureUnit].m_texture2DBinding = texture;
 
         if (!m_activeTextureUnit)
             drawingBuffer()->setTexture2DBinding(objectOrZero(texture));
+        bindingPointName = "texture_2d";
     } else if (target == GL_TEXTURE_CUBE_MAP) {
         m_textureUnits[m_activeTextureUnit].m_textureCubeMapBinding = texture;
+        bindingPointName = "texture_cube_map";
     } else if (isWebGL2OrHigher() && target == GL_TEXTURE_2D_ARRAY) {
         m_textureUnits[m_activeTextureUnit].m_texture2DArrayBinding = texture;
+        bindingPointName = "texture_2d_array";
     } else if (isWebGL2OrHigher() && target == GL_TEXTURE_3D) {
         m_textureUnits[m_activeTextureUnit].m_texture3DBinding = texture;
+        bindingPointName = "texture_3d";
     } else {
         synthesizeGLError(GL_INVALID_ENUM, "bindTexture", "invalid target");
         return;
     }
 
     webContext()->bindTexture(target, objectOrZero(texture));
+    // This is called both internally and externally (from JavaScript). We only update which wrapper
+    // is preserved when it's called from JavaScript.
+    if (scriptState) {
+        preserveObjectWrapper(scriptState, this, bindingPointName, m_activeTextureUnit, texture);
+    }
     if (texture) {
         texture->setTarget(target, getMaxTextureLevelForTarget(target));
         m_onePlusMaxNonDefaultTextureUnit = max(m_activeTextureUnit + 1, m_onePlusMaxNonDefaultTextureUnit);
     } else {
         // If the disabled index is the current maximum, trace backwards to find the new max enabled texture index
         if (m_onePlusMaxNonDefaultTextureUnit == m_activeTextureUnit + 1) {
             findNewMaxNonDefaultTextureUnit();
         }
     }
 
@@ skipping 409 matching lines @@
     if (isContextLost())
         return nullptr;
     if (!renderbuffer->emulatedStencilBuffer()) {
         renderbuffer->setEmulatedStencilBuffer(createRenderbuffer());
         webContext()->bindRenderbuffer(target, objectOrZero(renderbuffer->emulatedStencilBuffer()));
         webContext()->bindRenderbuffer(target, objectOrZero(m_renderbufferBinding.get()));
     }
     return renderbuffer->emulatedStencilBuffer();
 }
 
+void WebGLRenderingContextBase::setBoundVertexArrayObject(ScriptState* scriptState, WebGLVertexArrayObjectBase* arrayObject)
+{
+    if (arrayObject)
+        m_boundVertexArrayObject = arrayObject;
+    else
+        m_boundVertexArrayObject = m_defaultVertexArrayObject;
+
+    preserveObjectWrapper(scriptState, this, "boundvao", 0, arrayObject);
+}
+
 WebGLShader* WebGLRenderingContextBase::createShader(GLenum type)
 {
     if (isContextLost())
         return nullptr;
     if (type != GL_VERTEX_SHADER && type != GL_FRAGMENT_SHADER) {
         synthesizeGLError(GL_INVALID_ENUM, "createShader", "invalid shader type");
         return nullptr;
     }
 
     WebGLShader* o = WebGLShader::create(this, type);
@@ skipping 136 matching lines @@
 {
     if (isContextLost())
         return;
     if (zNear > zFar) {
         synthesizeGLError(GL_INVALID_OPERATION, "depthRange", "zNear > zFar");
         return;
     }
     webContext()->depthRange(zNear, zFar);
 }
 
-void WebGLRenderingContextBase::detachShader(WebGLProgram* program, WebGLShader* shader)
+void WebGLRenderingContextBase::detachShader(ScriptState* scriptState, WebGLProgram* program, WebGLShader* shader)
 {
     if (isContextLost() || !validateWebGLObject("detachShader", program) || !validateWebGLObject("detachShader", shader))
         return;
     if (!program->detachShader(shader)) {
         synthesizeGLError(GL_INVALID_OPERATION, "detachShader", "shader not attached");
         return;
     }
     webContext()->detachShader(objectOrZero(program), objectOrZero(shader));
     shader->onDetached(webContext());
+    preserveObjectWrapper(scriptState, program, "shader", shader->type(), nullptr);
 }
 
 void WebGLRenderingContextBase::disable(GLenum cap)
 {
     if (isContextLost() || !validateCapability("disable", cap))
         return;
     if (cap == GL_STENCIL_TEST) {
         m_stencilEnabled = false;
         applyStencilTest();
         return;
@@ skipping 139 matching lines @@
     webContext()->flush(); // Intentionally a flush, not a finish.
 }
 
 void WebGLRenderingContextBase::flush()
 {
     if (isContextLost())
         return;
     webContext()->flush();
 }
 
-void WebGLRenderingContextBase::framebufferRenderbuffer(GLenum target, GLenum attachment, GLenum renderbuffertarget, WebGLRenderbuffer* buffer)
+void WebGLRenderingContextBase::framebufferRenderbuffer(ScriptState* scriptState, GLenum target, GLenum attachment, GLenum renderbuffertarget, WebGLRenderbuffer* buffer)
 {
     if (isContextLost() || !validateFramebufferFuncParameters("framebufferRenderbuffer", target, attachment))
         return;
     if (renderbuffertarget != GL_RENDERBUFFER) {
         synthesizeGLError(GL_INVALID_ENUM, "framebufferRenderbuffer", "invalid target");
         return;
     }
     if (buffer && !buffer->validate(contextGroup(), this)) {
         synthesizeGLError(GL_INVALID_OPERATION, "framebufferRenderbuffer", "no buffer or buffer not from this context");
         return;
@@ skipping 27 matching lines @@
     }
     if (isWebGL2OrHigher() && attachment == GL_DEPTH_STENCIL_ATTACHMENT) {
         // On ES3, DEPTH_STENCIL_ATTACHMENT is like an alias for DEPTH_ATTACHMENT + STENCIL_ATTACHMENT.
         // We divide it here so in WebGLFramebuffer, we don't have to handle DEPTH_STENCIL_ATTACHMENT in WebGL 2.
         framebufferBinding->setAttachmentForBoundFramebuffer(target, GL_DEPTH_ATTACHMENT, buffer);
         framebufferBinding->setAttachmentForBoundFramebuffer(target, GL_STENCIL_ATTACHMENT, buffer);
     } else {
         framebufferBinding->setAttachmentForBoundFramebuffer(target, attachment, buffer);
     }
     applyStencilTest();
+    preserveObjectWrapper(scriptState, framebufferBinding, "renderbuffer", attachment, buffer);
 }
 
-void WebGLRenderingContextBase::framebufferTexture2D(GLenum target, GLenum attachment, GLenum textarget, WebGLTexture* texture, GLint level)
+void WebGLRenderingContextBase::framebufferTexture2D(ScriptState* scriptState, GLenum target, GLenum attachment, GLenum textarget, WebGLTexture* texture, GLint level)
 {
     if (isContextLost() || !validateFramebufferFuncParameters("framebufferTexture2D", target, attachment))
         return;
     if (isWebGL2OrHigher()) {
         if (!validateTexFuncLevel("framebufferTexture2D", textarget, level))
             return;
     } else if (level) {
         synthesizeGLError(GL_INVALID_VALUE, "framebufferTexture2D", "level not 0");
         return;
     }
@@ skipping 19 matching lines @@
         webContext()->framebufferTexture2D(target, attachment, textarget, textureObject, level);
         break;
     case GL_STENCIL_ATTACHMENT:
         webContext()->framebufferTexture2D(target, attachment, textarget, textureObject, level);
         break;
     default:
         webContext()->framebufferTexture2D(target, attachment, textarget, textureObject, level);
     }
     framebufferBinding->setAttachmentForBoundFramebuffer(target, attachment, textarget, texture, level);
     applyStencilTest();
+    preserveObjectWrapper(scriptState, framebufferBinding, "texture2d", attachment, texture);
 }
 
 void WebGLRenderingContextBase::frontFace(GLenum mode)
 {
     if (isContextLost())
         return;
     switch (mode) {
     case GL_CW:
     case GL_CCW:
         break;
@@ skipping 184 matching lines @@
     if (tracker->draft() && !RuntimeEnabledFeatures::webGLDraftExtensionsEnabled())
         return false;
     if (!tracker->supported(this))
         return false;
     return true;
 }
 
 ScriptValue WebGLRenderingContextBase::getExtension(ScriptState* scriptState, const String& name)
 {
     WebGLExtension* extension = nullptr;
+    bool linkContextToExtension = false;
 
     if (!isContextLost()) {
         for (size_t i = 0; i < m_extensions.size(); ++i) {
             ExtensionTracker* tracker = m_extensions[i];
             if (tracker->matchesNameWithPrefixes(name)) {
                 if (extensionSupportedAndAllowed(tracker)) {
                     extension = tracker->getExtension(this);
-                    if (extension)
-                        m_extensionEnabled[extension->name()] = true;
+                    if (extension) {
+                        if (!m_extensionEnabled[extension->name()]) {
+                            linkContextToExtension = true;
+                            m_extensionEnabled[extension->name()] = true;
+                        }
+                    }
                 }
                 break;
             }
         }
     }
 
-    return ScriptValue(scriptState, toV8(extension, scriptState->context()->Global(), scriptState->isolate()));
+    v8::Local<v8::Value> wrappedExtension = toV8(extension, scriptState->context()->Global(), scriptState->isolate());
+
+    if (linkContextToExtension) {
+        // Keep the extension's JavaScript wrapper alive as long as the context is alive, so that
+        // expando properties that are added to the extension persist.
+        preserveObjectWrapper(scriptState, this, "extension", static_cast<unsigned long>(extension->name()), extension);
+    }
+
+    return ScriptValue(scriptState, wrappedExtension);
 }
 
 ScriptValue WebGLRenderingContextBase::getFramebufferAttachmentParameter(ScriptState* scriptState, GLenum target, GLenum attachment, GLenum pname)
 {
     if (isContextLost() || !validateFramebufferFuncParameters("getFramebufferAttachmentParameter", target, attachment))
         return ScriptValue::createNull(scriptState);
 
     if (!m_framebufferBinding || !m_framebufferBinding->object()) {
         synthesizeGLError(GL_INVALID_OPERATION, "getFramebufferAttachmentParameter", "no framebuffer bound");
         return ScriptValue::createNull(scriptState);
@@ skipping 2257 matching lines @@
     webContext()->uniformMatrix4fv(location->location(), v->length() >> 4, transpose, v->data());
 }
 
 void WebGLRenderingContextBase::uniformMatrix4fv(const WebGLUniformLocation* location, GLboolean transpose, Vector<GLfloat>& v)
 {
     if (isContextLost() || !validateUniformMatrixParameters("uniformMatrix4fv", location, transpose, v.data(), v.size(), 16))
         return;
     webContext()->uniformMatrix4fv(location->location(), v.size() >> 4, transpose, v.data());
 }
 
-void WebGLRenderingContextBase::useProgram(WebGLProgram* program)
+void WebGLRenderingContextBase::useProgram(ScriptState* scriptState, WebGLProgram* program)
 {
     bool deleted;
     if (!checkObjectToBeBound("useProgram", program, deleted))
         return;
     if (deleted)
         program = 0;
     if (program && !program->linkStatus()) {
         synthesizeGLError(GL_INVALID_OPERATION, "useProgram", "program not valid");
         return;
     }
     if (m_currentProgram != program) {
         if (m_currentProgram)
             m_currentProgram->onDetached(webContext());
         m_currentProgram = program;
         webContext()->useProgram(objectOrZero(program));
         if (program)
             program->onAttached();
+        preserveObjectWrapper(scriptState, this, "program", 0, program);
     }
 }
 
 void WebGLRenderingContextBase::validateProgram(WebGLProgram* program)
 {
     if (isContextLost() || !validateWebGLObject("validateProgram", program))
         return;
     webContext()->validateProgram(objectOrZero(program));
 }
 
@@ skipping 50 matching lines @@
 void WebGLRenderingContextBase::vertexAttrib4fv(GLuint index, const DOMFloat32Array* v)
 {
     vertexAttribfvImpl("vertexAttrib4fv", index, v, 4);
 }
 
 void WebGLRenderingContextBase::vertexAttrib4fv(GLuint index, const Vector<GLfloat>& v)
 {
     vertexAttribfvImpl("vertexAttrib4fv", index, v.data(), v.size(), 4);
 }
 
-void WebGLRenderingContextBase::vertexAttribPointer(GLuint index, GLint size, GLenum type, GLboolean normalized, GLsizei stride, long long offset)
+void WebGLRenderingContextBase::vertexAttribPointer(ScriptState* scriptState, GLuint index, GLint size, GLenum type, GLboolean normalized, GLsizei stride, long long offset)
 {
     if (isContextLost())
         return;
     switch (type) {
     case GL_BYTE:
     case GL_UNSIGNED_BYTE:
     case GL_SHORT:
     case GL_UNSIGNED_SHORT:
     case GL_FLOAT:
         break;
@@ skipping 18 matching lines @@
     unsigned typeSize = sizeInBytes(type);
     ASSERT((typeSize & (typeSize - 1)) == 0); // Ensure that the value is POT.
     if ((stride & (typeSize - 1)) || (static_cast<GLintptr>(offset) & (typeSize - 1))) {
         synthesizeGLError(GL_INVALID_OPERATION, "vertexAttribPointer", "stride or offset not valid for type");
         return;
     }
     GLsizei bytesPerElement = size * typeSize;
 
     m_boundVertexArrayObject->setVertexAttribState(index, bytesPerElement, size, type, normalized, stride, static_cast<GLintptr>(offset), m_boundArrayBuffer);
     webContext()->vertexAttribPointer(index, size, type, normalized, stride, static_cast<GLintptr>(offset));
+    maybePreserveDefaultVAOObjectWrapper(scriptState);
+    preserveObjectWrapper(scriptState, m_boundVertexArrayObject, "arraybuffer", index, m_boundArrayBuffer);

[bajones, 2015/10/03 14:39:23]

I don't think so, but just so we're clear: This won't prevent developers for
attaching an "arraybuffer" property  (or other names used throughout this patch)
to the context in their scripts? If so I have some (very very tiny) concerns
about behavior regression and think we should use more obfuscated named.

[Ken Russell (switch to Gerrit), 2015/10/05 22:42:03]

No. These properties don't show up on the object. I triple-checked this by
adding printf logging and using every JavaScript API I could think of to fetch
these hidden properties, and they aren't visible at the user level.

 }
 
 void WebGLRenderingContextBase::vertexAttribDivisorANGLE(GLuint index, GLuint divisor)
 {
     if (isContextLost())
         return;
 
     if (index >= m_maxVertexAttribs) {
         synthesizeGLError(GL_INVALID_VALUE, "vertexAttribDivisorANGLE", "index out of range");
         return;
@@ skipping 101 matching lines @@
     return isContextLost() ? 0 : drawingBuffer()->platformLayer();
 }
 
 void WebGLRenderingContextBase::setFilterQuality(SkFilterQuality filterQuality)
 {
     if (!isContextLost() && drawingBuffer()) {
         drawingBuffer()->setFilterQuality(filterQuality);
     }
 }
 
+void WebGLRenderingContextBase::preserveObjectWrapper(ScriptState* scriptState, ScriptWrappable* sourceObject, const char* baseName, unsigned long index, ScriptWrappable* targetObject)
+{
+    v8::Local<v8::Value> value;
+
+    StringBuilder builder;
+    builder.append(baseName);
+    builder.appendNumber(static_cast<unsigned>(index));
+    CString name = builder.toString().utf8();
+    if (targetObject) {
+        value = targetObject->newLocalWrapper(scriptState->isolate());
+    } else {
+        value = v8::Null(scriptState->isolate());
+    }
+
+    V8HiddenValue::setHiddenValue(
+        scriptState->isolate(),
+        sourceObject->newLocalWrapper(scriptState->isolate()),
+        v8::String::NewFromUtf8(
+            scriptState->isolate(),
+            name.data(),
+            v8::NewStringType::kNormal,
+            name.length()).ToLocalChecked(),
+        value);
+}
+
 Extensions3DUtil* WebGLRenderingContextBase::extensionsUtil()
 {
     if (!m_extensionsUtil) {
         m_extensionsUtil = Extensions3DUtil::create(webContext());
         // The only reason the ExtensionsUtil should be invalid is if the webContext is lost.
         ASSERT(m_extensionsUtil->isValid() || webContext()->isContextLost());
     }
     return m_extensionsUtil.get();
 }
 
@@ skipping 1521 matching lines @@
     if (!buffer) {
         // Instead of binding fb 0, bind the drawing buffer.
         drawingBuffer()->bind(target);
     } else {
         webContext()->bindFramebuffer(target, buffer->object());
     }
 }
 
 void WebGLRenderingContextBase::restoreCurrentFramebuffer()
 {
-    bindFramebuffer(GL_FRAMEBUFFER, m_framebufferBinding.get());
+    bindFramebuffer(nullptr, GL_FRAMEBUFFER, m_framebufferBinding.get());
 }
 
 void WebGLRenderingContextBase::restoreCurrentTexture2D()
 {
-    bindTexture(GL_TEXTURE_2D, m_textureUnits[m_activeTextureUnit].m_texture2DBinding.get());
+    bindTexture(nullptr, GL_TEXTURE_2D, m_textureUnits[m_activeTextureUnit].m_texture2DBinding.get());
 }
 
 void WebGLRenderingContextBase::multisamplingChanged(bool enabled)
 {
     if (m_multisamplingAllowed != enabled) {
         m_multisamplingAllowed = enabled;
         forceLostContext(WebGLRenderingContextBase::SyntheticLostContext, WebGLRenderingContextBase::Auto);
     }
 }
 
 void WebGLRenderingContextBase::findNewMaxNonDefaultTextureUnit()
 {
     // Trace backwards from the current max to find the new max non-default texture unit
     int startIndex = m_onePlusMaxNonDefaultTextureUnit - 1;
     for (int i = startIndex; i >= 0; --i) {
         if (m_textureUnits[i].m_texture2DBinding
             || m_textureUnits[i].m_textureCubeMapBinding) {
             m_onePlusMaxNonDefaultTextureUnit = i + 1;
             return;
         }
     }
     m_onePlusMaxNonDefaultTextureUnit = 0;
 }
 
+void WebGLRenderingContextBase::maybePreserveDefaultVAOObjectWrapper(ScriptState* scriptState)
+{
+    if (!m_preservedDefaultVAOObjectWrapper) {
+        // The default VAO does not have a JavaScript wrapper created for it, but one is needed to
+        // link up the WebGLBuffers associated with the vertex attributes.
+        m_defaultVertexArrayObject->wrap(scriptState->isolate(), scriptState->context()->Global());
+        preserveObjectWrapper(scriptState, this, "defaultvao", 0, m_defaultVertexArrayObject);
+        m_preservedDefaultVAOObjectWrapper = true;
+    }
+}
+
 DEFINE_TRACE(WebGLRenderingContextBase::TextureUnitState)
 {
     visitor->trace(m_texture2DBinding);
     visitor->trace(m_textureCubeMapBinding);
     visitor->trace(m_texture3DBinding);
     visitor->trace(m_texture2DArrayBinding);
 }
 
 DEFINE_TRACE(WebGLRenderingContextBase)
 {
@@ skipping 42 matching lines @@
 
     return totalBytesPerPixel;
 }
 
 DrawingBuffer* WebGLRenderingContextBase::drawingBuffer() const
 {
     return m_drawingBuffer.get();
 }
 
 } // namespace blink