Reduce size of TypeScript Compiler snapshot (#6809)

This PR is intentionally ugly. It duplicates all of the code in cli/js2/ into
cli/tsc/  ... because it's very important that we all understand that this code
is unnecessarily duplicated in our binary. I hope this ugliness provides the
motivation to clean it up.

The typescript git submodule is removed, because it's a very large repo and
contains all sorts of stuff we don't need. Instead the necessary files are
copied directly into the deno repo. Hence +200k lines.

COMPILER_SNAPSHOT.bin size
```
master         3448139
this branch    3320972
```

Fixes #6812

1 files changed, 27 insertions, 0 deletions

diff --git a/cli/tsc/40_diagnostics.js b/cli/tsc/40_diagnostics.js
new file mode 100644
index 000000000..110d3d767
--- /dev/null
+++ b/cli/tsc/40_diagnostics.js
@@ -0,0 +1,27 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+// Diagnostic provides an abstraction for advice/errors received from a
+// compiler, which is strongly influenced by the format of TypeScript
+// diagnostics.
+
+((window) => {
+  const DiagnosticCategory = {
+    0: "Log",
+    1: "Debug",
+    2: "Info",
+    3: "Error",
+    4: "Warning",
+    5: "Suggestion",
+
+    Log: 0,
+    Debug: 1,
+    Info: 2,
+    Error: 3,
+    Warning: 4,
+    Suggestion: 5,
+  };
+
+  window.__bootstrap.diagnostics = {
+    DiagnosticCategory,
+  };
+})(this);