Check malformed mutability on imported globals (#6679)

And re-enable the globals.wast spec test, which checks this.

Author: tlively

scripts/test/shared.py

@@ -400,7 +400,6 @@ def get_tests(test_dir, extensions=[], recursive=False):
 # expected-output/ if any.
 SPEC_TESTS_TO_SKIP = [
     # Malformed module accepted
-    'globals.wast',
     'binary-leb128.wast',
     'utf8-custom-section-id.wast',
     'utf8-import-field.wast',

src/wasm/wasm-binary.cpp

@@ -2591,6 +2591,9 @@ void WasmBinaryReader::readImports() {
         Name name(std::string("gimport$") + std::to_string(globalCounter++));
         auto type = getConcreteType();
         auto mutable_ = getU32LEB();
+        if (mutable_ & ~1) {
+          throwError("Global mutability must be 0 or 1");
+        }
         auto curr =
           builder.makeGlobal(name,
                              type,