Bug 1184786 - Fix LastColorAttachment(). r=jgilbert

dom/canvas/WebGLContext.h

@@ -1403,10 +1403,8 @@ protected:
     WebGLRefPtr<WebGLProgram> mCurrentProgram;
     RefPtr<const webgl::LinkedProgramInfo> mActiveProgramLinkInfo;
 
-    uint32_t mMaxFramebufferColorAttachments;
-
     GLenum LastColorAttachment() const {
-        return LOCAL_GL_COLOR_ATTACHMENT0 + mMaxFramebufferColorAttachments - 1;
+        return LOCAL_GL_COLOR_ATTACHMENT0 + mGLMaxColorAttachments - 1;
     }
 
     bool ValidateFramebufferTarget(GLenum target, const char* const info);

dom/canvas/WebGLContextValidate.cpp

@@ -401,15 +401,8 @@ WebGLContext::ValidateFramebufferAttachment(const WebGLFramebuffer* fb, GLenum a
         return true;
     }
 
-    GLenum colorAttachCount = 1;
-    if (IsExtensionEnabled(WebGLExtensionID::WEBGL_draw_buffers))
-        colorAttachCount = mGLMaxColorAttachments;
-
-    if (attachment >= LOCAL_GL_COLOR_ATTACHMENT0 &&
-        attachment < GLenum(LOCAL_GL_COLOR_ATTACHMENT0 + colorAttachCount))
-    {
+    if (attachment >= LOCAL_GL_COLOR_ATTACHMENT0 && attachment <= LastColorAttachment())
         return true;
-    }
 
     ErrorInvalidEnum("%s: attachment: invalid enum value 0x%x.", funcName,
                      attachment);
@@ -1885,9 +1878,6 @@ WebGLContext::InitAndValidateGL()
         }
     }
 
-    // Always 1 for GLES2
-    mMaxFramebufferColorAttachments = 1;
-
     if (gl->IsCompatibilityProfile()) {
         // gl_PointSize is always available in ES2 GLSL, but has to be
         // specifically enabled on desktop GLSL.