Implement OES_texture_float_linear and OES_texture_half_float_linear extensions in WebGL.

Source/core/html/canvas/WebGLExtension.h

Index: Source/core/html/canvas/WebGLExtension.h
diff --git a/Source/core/html/canvas/WebGLExtension.h b/Source/core/html/canvas/WebGLExtension.h
index 2a481e0a52bcd7f568782750d30409b641ed3c66..2e03b8edf5990bb3e2353926acf3bdc66c0afda5 100644
--- a/Source/core/html/canvas/WebGLExtension.h
+++ b/Source/core/html/canvas/WebGLExtension.h
@@ -49,6 +49,8 @@ public:
         OESElementIndexUintName,
         WebGLCompressedTextureATCName,
         WebGLCompressedTexturePVRTCName,
+        OESTextureFloatLinearName,
+        OESTextureHalfFloatLinearName,
     };
 
     void ref() { m_context->ref(); }