Revert of Fix iOS build. (https://codereview.chromium.org/269663008/)

Reason for revert:
Reverting as this is a follow on to https://codereview.chromium.org/243413002/ which is breaking android debug bots

Original issue's description:
> Fix iOS build.
>
> Committed: https://code.google.com/p/skia/source/detail?r=14537

R=bsalomon@google.com
TBR=bsalomon@google.com
NOTREECHECKS=true
NOTRY=true

Author: djsollen@google.com

Review URL: https://codereview.chromium.org/261983002

git-svn-id: http://skia.googlecode.com/svn/trunk@14539 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/gl/iOS/GrGLCreateNativeInterface_iOS.cpp b/src/gpu/gl/iOS/GrGLCreateNativeInterface_iOS.cpp
index 08e7ac8..d61afbd 100644
--- a/src/gpu/gl/iOS/GrGLCreateNativeInterface_iOS.cpp
+++ b/src/gpu/gl/iOS/GrGLCreateNativeInterface_iOS.cpp
@@ -133,8 +133,8 @@
 #endif
 
 #if GL_EXT_map_buffer_range || GL_ES_VERSION_3_0
-    functions->fMapBufferRange = glMapBufferRangeEXT;
-    functions->fFlushMappedBufferRange = glFlushMappedBufferRangeEXT;
+    functions->fMapBufferRange = glMapBufferRange;
+    functions->fFlushMappedBufferRange = glFlushMappedBufferRange;
 #endif
 
 #if GL_APPLE_framebuffer_multisample