Add GLES1 targets and stub entry points.

 * Create a new libGLESv1_CM target.
 * Merge all autogenerated extension entry points into one file.
 * Allow creation of ES1 contexts.

BUG=angleproject:2306

Change-Id: I446258363a96a3c37d657089dd7c1cff0fa3cf78
Reviewed-on: https://chromium-review.googlesource.com/865718
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/Config.cpp b/src/libANGLE/Config.cpp
index ccf64c8..18019ee 100644
--- a/src/libANGLE/Config.cpp
+++ b/src/libANGLE/Config.cpp
@@ -300,4 +300,13 @@
     return result;
 }
 
+ConfigSet::ConfigMap::iterator ConfigSet::begin()
+{
+    return mConfigs.begin();
+}
+
+ConfigSet::ConfigMap::iterator ConfigSet::end()
+{
+    return mConfigs.end();
+}
 }