document various v8 bugs

closes mishoo#4805

README.md

@@ -1296,3 +1296,16 @@ To allow for better optimizations, the compiler makes various assumptions:
   // SyntaxError: Identifier 'e' has already been declared
   ```
   UglifyJS may modify the input which in turn may suppress those errors.
+- Some versions of Chrome and Node.js will give incorrect results with the
+  following:
+  ```javascript
+  console.log({
+      ...{
+          set 42(v) {},
+          42: "PASS",
+      },
+  });
+  // Expected: { '42': 'PASS' }
+  // Actual:   { '42': undefined }
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.

test/compress/classes.js

@@ -725,7 +725,7 @@ unused_await: {
             (() => console.log(await))();
         })();
     }
-    expect_stdout: "PASS"
+    expect_stdout: true
     node_version: ">=12"
 }
 

test/compress/loops.js

@@ -836,10 +836,7 @@ for_of: {
             console.log(async);
     }
     expect_exact: 'var async=["PASS",42];async.p="FAIL";for(async of(null,async))console.log(async);'
-    expect_stdout: [
-        "PASS",
-        "42",
-    ]
+    expect_stdout: true
     node_version: ">=0.12"
 }
 

test/ufuzz/index.js

@@ -2401,6 +2401,9 @@ if (SUPPORT.destructuring && typeof sandbox.run_code("console.log([ 1 ], {} = 2)
         o.output.v8 = true;
     });
 }
+if (SUPPORT.exponentiation && sandbox.run_code("console.log(10 ** 100 === Math.pow(10, 100));") !== "true\n") {
+    SUPPORT.exponentiation = false;
+}
 beautify_options = JSON.stringify(beautify_options);
 minify_options = minify_options.map(JSON.stringify);
 var original_code, original_result, errored;