[wasm] Enable and fix wasm exceptions WPTs

For most tests, expectations were deleted since the tests now pass.

The getArg test was corrected to match the spec:
https://webassembly.github.io/exception-handling/js-api/index.html#dom-exception-getarg

The tag type test had its expectations updated, but is still
(incorrectly) failing because the test also depends on the not-yet-shipped
type reflection proposal. Updated the spec bug to bring this conversation
back to the spec (WebAssembly/exception-handling#172).

Bug: v8:11992
Change-Id: I979a9eb00219e0b9515d43bbeff6f80ac57df7c9

wasm/jsapi/exception/getArg.tentative.any.js

@@ -20,7 +20,7 @@ test(() => {
 test(() => {
   const tag = new WebAssembly.Tag({ parameters: [] });
   const exn = new WebAssembly.Exception(tag, []);
-  assert_throws_js(TypeError, () => exn.getArg(tag, 1));
+  assert_throws_js(RangeError, () => exn.getArg(tag, 1));
 }, "Index out of bounds");
 
 test(() => {