Revert of WebGL 2: generate appropriate error for different dimensions of...

Revert of WebGL 2: generate appropriate error for different dimensions of images attached to fbo (patchset #1 id:1 of https://codereview.chromium.org/1549393002/ )

Reason for revert:
This broke the WebglConformance.conformance2_rendering_draw_buffers test on mac.

Original issue's description:
> WebGL 2: generate appropriate error for different dimensions of images attached to fbo.
> This change fixed the bug in framebuffer-object-attachment.html
>
> BUG=295792
> TEST=conformance2/renderbuffers/framebuffer-object-attachment.html
>
> Committed: https://crrev.com/23cf53ece33a651b28a1d87e57f02a14f22d3c3d
> Cr-Commit-Position: refs/heads/master@{#367053}

TBR=kbr@chromium.org,zmo@chromium.org,bajones@chromium.org,qiankun.miao@intel.com,yunchao.he@intel.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=295792

Review URL: https://codereview.chromium.org/1555543002

Cr-Commit-Position: refs/heads/master@{#367070}

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

@@ -46,7 +46,6 @@ private:
 
     GLsizei width() const override;
     GLsizei height() const override;
-    GLsizei depth() const override;
     GLenum format() const override;
     GLenum type() const override;
     bool isCubeComplete() const override;
@@ -86,11 +85,6 @@ GLsizei WebGLRenderbufferAttachment::height() const
     return m_renderbuffer->height();
 }
 
-GLsizei WebGLRenderbufferAttachment::depth() const
-{
-    return 1;
-}
-
 GLenum WebGLRenderbufferAttachment::format() const
 {
     GLenum format = m_renderbuffer->internalFormat();
@@ -166,7 +160,6 @@ private:
 
     GLsizei width() const override;
     GLsizei height() const override;
-    GLsizei depth() const override;
     GLenum format() const override;
     GLenum type() const override;
     bool isCubeComplete() const override;
@@ -212,11 +205,6 @@ GLsizei WebGLTextureAttachment::height() const
     return m_texture->getHeight(m_target, m_level);
 }
 
-GLsizei WebGLTextureAttachment::depth() const
-{
-    return m_texture->getDepth(m_target, m_level);
-}
-
 GLenum WebGLTextureAttachment::format() const
 {
     return m_texture->getInternalFormat(m_target, m_level);
@@ -551,7 +539,7 @@ GLenum WebGLFramebuffer::colorBufferFormat() const
 GLenum WebGLFramebuffer::checkStatus(const char** reason) const
 {
     unsigned count = 0;
-    GLsizei width = 0, height = 0, depth = 0;
+    GLsizei width = 0, height = 0;
     WebGLAttachment* depthAttachment = nullptr;
     WebGLAttachment* stencilAttachment = nullptr;
     WebGLAttachment* depthStencilAttachment = nullptr;
@@ -579,20 +567,17 @@ GLenum WebGLFramebuffer::checkStatus(const char** reason) const
             depthStencilAttachment = attachment;
             break;
         }
-        // Note: In GLES 3, images for a framebuffer need not to have the same dimensions to be framebuffer complete.
-        // However, in Direct3D 11, on top of which OpenGL ES 3 behavior is emulated in Windows, all render targets
-        // must have the same size in all dimensions. In order to have consistent WebGL 2 behaviors across platforms,
-        // we generate FRAMEBUFFER_INCOMPLETE_DIMENSIONS in this situation.
+        if (!isWebGL2OrHigher) {
             if (!count) {
                 width = attachment->width();
                 height = attachment->height();
-            depth = attachment->depth();
             } else {
-            if (width != attachment->width() || height != attachment->height() || depth != attachment->depth()) {
+                if (width != attachment->width() || height != attachment->height()) {
                     *reason = "attachments do not have the same dimensions";
                     return GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS;
                 }
             }
+        }
         ++count;
     }
     if (!count) {

third_party/WebKit/Source/modules/webgl/WebGLFramebuffer.h

@@ -43,7 +43,6 @@ public:
 
         virtual GLsizei width() const = 0;
         virtual GLsizei height() const = 0;
-        virtual GLsizei depth() const = 0;
         virtual GLenum format() const = 0;
         // For texture attachment, type() returns the type of the attached texture.
         // For renderbuffer attachment, the type of the renderbuffer may vary with GL implementation.