Fix typos discovered by codespell (#1496)

# https://pypi.org/project/codespell
% `codespell`
```
./emsdk.py:1459: thier ==> their
./test/test.bat:1: equivilent ==> equivalent
./test/test.py:198: Specificlly ==> Specifically
./scripts/update_bazel_workspace.py:2: revisons ==> revisions
./scripts/update_node.py:11: direcotry ==> directory
./bazel/emscripten_toolchain/BUILD.bazel:57: implictly ==> implicitly
./docker/Dockerfile:87: terninal ==> terminal
```

scripts/update_node.py

@@ -8,7 +8,7 @@
 http://storage.google.com/webassembly.
 
 For the windows version we also alter the directory layout to add the 'bin'
-direcotry.
+directory.
 """
 
 import urllib.request