[wasm] Remove 'using namespace' from wasm-objects.cc

This violated the style guide, and caused problems for jumbo builds.

R=titzer@chromium.org
CC=mostynb@opera.com

Bug: chromium:746958
Change-Id: Iaa75d444f5b5f595c54058de14b394119390921c
Reviewed-on: https://chromium-review.googlesource.com/645529
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47744}

src/wasm/wasm-objects.h

@@ -27,7 +27,7 @@ class WasmInterpreter;
 // When we compile or instantiate, we need to create global handles
 // for function tables. Normally, these handles get destroyed when the
 // respective objects get GCed. If we fail to construct those objects,
-// we can leak global hanles. The exit path in these cases isn't unique,
+// we can leak global handles. The exit path in these cases isn't unique,
 // and may grow.
 //
 // This type addresses that.