WebGL backbuffer creation on Mali-400 GPU

Source/core/html/canvas/WebGLRenderingContextBase.cpp

Index: Source/core/html/canvas/WebGLRenderingContextBase.cpp
diff --git a/Source/core/html/canvas/WebGLRenderingContextBase.cpp b/Source/core/html/canvas/WebGLRenderingContextBase.cpp
index c042e9733c01fc3c39b51f5bc61044aca0247b66..1be77627ede3ced873072b73fc4280476c4d5f9a 100644
--- a/Source/core/html/canvas/WebGLRenderingContextBase.cpp
+++ b/Source/core/html/canvas/WebGLRenderingContextBase.cpp
@@ -1450,6 +1450,9 @@ void WebGLRenderingContextBase::colorMask(GLboolean red, GLboolean green, GLbool
 {
     if (isContextLost())
         return;
+    // Disable alpha writes, if requested alpha attribute is false & backbuffer allocated as GL_RGBA
+    if (!m_requestedAttributes.alpha() && !drawingBuffer()->isRGBTextureSupported())
+        alpha = '\0';

[Ken Russell (switch to Gerrit), 2015/04/06 21:43:18]

That's a strange way to write that constant. Please use alpha = false or
GL_FALSE.

     m_colorMask[0] = red;
     m_colorMask[1] = green;
     m_colorMask[2] = blue;
@@ -2342,7 +2345,10 @@ ScriptValue WebGLRenderingContextBase::getParameter(ScriptState* scriptState, GL
     case GL_ALIASED_POINT_SIZE_RANGE:
         return getWebGLFloatArrayParameter(scriptState, pname);
     case GL_ALPHA_BITS:
-        return getIntParameter(scriptState, pname);
+        // Report 0 bits, if requested alpha attribute is false & backbuffer allocated as GL_RGBA
+        return (!m_requestedAttributes.alpha() && !drawingBuffer()->isRGBTextureSupported()) > 0

[Ken Russell (switch to Gerrit), 2015/04/06 21:43:18]

This is a strange way to write a boolean test. Please drop the "> 0".

+            ? WebGLAny(scriptState, intZero)
+            : getIntParameter(scriptState, pname);

[Ken Russell (switch to Gerrit), 2015/04/06 21:43:18]

Please also fix up the query of COLOR_WRITEMASK.

     case GL_ARRAY_BUFFER_BINDING:
         return WebGLAny(scriptState, PassRefPtrWillBeRawPtr<WebGLObject>(m_boundArrayBuffer.get()));
     case GL_BLEND: