Add quickjs-2021-03-27 to third_party

third_party/quickjs/TODO

@@ -0,0 +1,70 @@
+Bugs:
+- modules: better error handling with cyclic module references
+
+Misc ideas:
+- use custom printf to avoid compatibility issues with floating point numbers
+- consistent naming for preprocessor defines
+- unify coding style and naming conventions
+- use names from the ECMA spec in library implementation
+- use byte code emitters with typed arguments (for clarity)
+- use 2 bytecode DynBufs in JSFunctionDef, one for reading, one for writing
+  and use the same wrappers in all phases
+- use more generic method for line numbers in resolve_variables and resolve_labels
+- use custom timezone support to avoid C library compatibility issues
+
+Memory:
+- use memory pools for objects, etc?
+- test border cases for max number of atoms, object properties, string length
+- add emergency malloc mode for out of memory exceptions.
+- test all DynBuf memory errors
+- test all js_realloc memory errors
+- improve JS_ComputeMemoryUsage() with more info
+
+Built-in standard library:
+- BSD sockets
+- modules: use realpath in module name normalizer and put it in quickjs-libc
+- modules: if no ".", use a well known module loading path ?
+- get rid of __loadScript, use more common name
+
+REPL:
+- debugger
+- readline: support MS Windows terminal
+- readline: handle dynamic terminal resizing
+- readline: handle double width unicode characters
+- multiline editing
+- runtime object and function inspectors
+- interactive object browser
+- use more generic approach to display evaluation results
+- improve directive handling: dispatch, colorize, completion...
+- save history
+- close all predefined methods in repl.js and jscalc.js
+
+Optimization ideas:
+- 64-bit atoms in 64-bit mode ?
+- 64-bit small bigint in 64-bit mode ?
+- reuse stack slots for disjoint scopes, if strip
+- add heuristic to avoid some cycles in closures
+- small String (0-2 charcodes) with immediate storage
+- perform static string concatenation at compile time
+- optimize string concatenation with ropes or miniropes?
+- add implicit numeric strings for Uint32 numbers?
+- optimize `s += a + b`, `s += a.b` and similar simple expressions
+- ensure string canonical representation and optimise comparisons and hashes?
+- remove JSObject.first_weak_ref, use bit+context based hashed array for weak references
+- property access optimization on the global object, functions,
+  prototypes and special non extensible objects.
+- create object literals with the correct length by backpatching length argument
+- remove redundant set_loc_uninitialized/check_uninitialized opcodes
+- peephole optim: push_atom_value, to_propkey -> push_atom_value
+- peephole optim: put_loc x, get_loc_check x -> set_loc x
+- convert slow array to fast array when all properties != length are numeric
+- optimize destructuring assignments for global and local variables
+- implement some form of tail-call-optimization
+- optimize OP_apply
+- optimize f(...b)
+
+Test262o:   0/11262 errors, 463 excluded
+Test262o commit: 7da91bceb9ce7613f87db47ddd1292a2dda58b42 (es5-tests branch)
+
+Result: 35/75280 errors, 909 excluded, 585 skipped
+Test262 commit: 31126581e7290f9233c29cefd93f66c6ac78f1c9