Make GL_ANGLE_framebuffer_multisample enableable.

BUG=angleproject:1523

Change-Id: Idc2cf338ba1fb5142ef2596603d291790fd6ddd6
Reviewed-on: https://chromium-review.googlesource.com/688100
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/State.cpp b/src/libANGLE/State.cpp
index 888a293..32029f6 100644
--- a/src/libANGLE/State.cpp
+++ b/src/libANGLE/State.cpp
@@ -191,11 +191,8 @@
     mDebug.setOutputEnabled(debug);
     mDebug.setMaxLoggedMessages(extensions.maxDebugLoggedMessages);
 
-    if (extensions.framebufferMultisample)
-    {
-        mMultiSampling = true;
-        mSampleAlphaToOne = false;
-    }
+    mMultiSampling    = true;
+    mSampleAlphaToOne = false;
 
     mCoverageModulation = GL_NONE;