Some types of variables are missing scopes

[pbarbiero]

Prerequisites

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Description

In atom 1.34, I am trying to update my syntax sheet that worked with the old syntax parser to take advantage of the tree-sitter parsers. Without any other extension enabled, the examples below are just from toggling the use tree sitter parsers option. (examples below are using https://github.com/thomaslindstrom/no-caffeine-syntax)

Steps to Reproduce

Edit by @rsese to add code for copy/paste

function functionName(param1, param2, param3) {}
function functionName(param1, param2, param3 = 1) {}
functionName(param1, param2).then((result) => {});
functionName(param1, param2).then(({ result }) => {});
const newThing = calculate(param1, store.getState())

Have code like this with tree sitter parsers disabled:

Enable tree sitter parsers, and your code will look like this:

Problems seen between the two:
Line 1: No problems
Line 2: No scope present for param3
Line 3: No scope present for param1 and param2
Line 4: Same as line 3 except also no scope present for result
Line 5: No scope present for param and store

Notes:
line 4 lets me differentiate result from result in line 3
line 5 lets me differentiate store from param1

Expected behavior: All variables would have the unique scopes to target styles like we could with the old parser

Actual behavior: New parser does not target some variables with scopes to allow consistent styling with the old parser

Reproduces how often: 100%

Versions

Atom 1.34.0
Electron 2.0.16
Chrome 61.0.3163.100
Node v8.9.3

Additional

See #630

[rsese]

Thanks for creating a new issue for this @pbarbiero - reproduced with 1.34.0 on macOS 10.12.6.