Web: Selectively remove a few key features, using #ifndef GLSLANG_WEB

Save about 100K.

N.B.: This is done by eliminating a function call, at a high level,
not by #ifdef'ing a bunch of code.

Also, removed no longer needed *_EXTENSION #ifdef in the code not
needed by GLSLANG_WEB.
diff --git a/Test/runtests b/Test/runtests
index c50f148..cf947a6 100755
--- a/Test/runtests
+++ b/Test/runtests
@@ -55,8 +55,8 @@
 # multi-threaded test
 #
 echo Comparing single thread to multithread for all tests in current directory...
-$EXE -i -C *.vert *.geom *.frag *.tes* *.comp > singleThread.out
-$EXE -i -C *.vert *.geom *.frag *.tes* *.comp -t > multiThread.out
+$EXE -i -C *.vert *.geom *.frag *.tesc *.tese *.comp > singleThread.out
+$EXE -i -C *.vert *.geom *.frag *.tesc *.tese *.comp -t > multiThread.out
 diff singleThread.out multiThread.out || HASERROR=1
 if [ $HASERROR -eq 0 ]
 then