Support ES 3.0 constants for bufferData's usage argument.

Source/modules/webgl/WebGL2RenderingContextBase.cpp

Index: Source/modules/webgl/WebGL2RenderingContextBase.cpp
diff --git a/Source/modules/webgl/WebGL2RenderingContextBase.cpp b/Source/modules/webgl/WebGL2RenderingContextBase.cpp
index 234cbd6fbd2a8383012c72629f347131e8395dbd..fa95cfa7c3d154cb2a815963c1ec4cbbca891465 100644
--- a/Source/modules/webgl/WebGL2RenderingContextBase.cpp
+++ b/Source/modules/webgl/WebGL2RenderingContextBase.cpp
@@ -1594,9 +1594,13 @@ void WebGL2RenderingContextBase::resumeTransformFeedback()
 
 void WebGL2RenderingContextBase::bindBufferBase(GLenum target, GLuint index, WebGLBuffer* buffer)
 {
-    if (isContextLost() || !validateWebGLObject("bindBufferBase", buffer))
+    if (isContextLost())
         return;
-
+    bool deleted;
+    if (!checkObjectToBeBound("bindBufferBase", buffer, deleted))
+        return;
+    if (deleted)
+        buffer = 0;

[Zhenyao Mo, 2015/08/31 18:30:56]

By the way, the spec says "If the buffer object named buffer has not been
previously bound, or has been deleted since the last binding, the GL creates a
new state vector, initialized with a zero-sized memory buffer and comprising all
the state and with the same initial values listed in table 2.7.", so it seems
like the deleted object being revised.  In that case, will passing 0 to the GL
driver be correct behavior?

[Ken Russell (switch to Gerrit), 2015/08/31 18:41:53]

It seems to me there isn't any difference in behavior here between for example
BindBuffer and BindBufferBase; they both have the same spec language around
deleted objects. Since WebGL forbids reviving deleted objects, I think this
behavior is OK (though it should certainly be tested).

     webContext()->bindBufferBase(target, index, objectOrZero(buffer));
 }
 
@@ -2450,6 +2454,21 @@ WebGLBuffer* WebGL2RenderingContextBase::validateBufferDataTarget(const char* fu
     return buffer;
 }
 
+bool WebGL2RenderingContextBase::validateBufferDataUsage(const char* functionName, GLenum usage)
+{
+    switch (usage) {
+    case GL_STREAM_READ:
+    case GL_STREAM_COPY:
+    case GL_STATIC_READ:
+    case GL_STATIC_COPY:
+    case GL_DYNAMIC_READ:
+    case GL_DYNAMIC_COPY:
+        return true;
+    default:
+        return WebGLRenderingContextBase::validateBufferDataUsage(functionName, usage);
+    }
+}
+
 void WebGL2RenderingContextBase::removeBoundBuffer(WebGLBuffer* buffer)
 {
     if (m_boundCopyReadBuffer == buffer)