**Description:**
This PR improves the alias analyzer by distinguishing call and reference, thus reducing the number of identifiers.
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Co-authored-by: Justin Ridgewell <justin@ridgewell.name>
**Description:**
As our minifier is two-pass by default, this is enough.
At the first pass, we inline all numeric literals using sequential inliner, and minifier can then inline constants correctly in the second pass.
**Description:**
This PR renames `CloningMultiReplacer` to `Finalizer` and makes it handle the removal of unused variables. Also, this PR improves the sequential inliner so we can drop variables within a single pass.
**Description:**
We had two passes for joining variables. This PR removes one in the full optimizer, which is wrong.
**Related issue:**
- Closes https://github.com/swc-project/swc/issues/5989.
**Description:**
This patch applies the variable collapsing logic for the variables declared with `var` to the variables declared with `let`. This requires some patch about the behavior of visitors about `BlockStmt`, so this patch includes relevant changes.
**Related issue:**
- Closes https://github.com/swc-project/swc/issues/5696.
**Description:**
Invoke DCE only before the first compression. I verified that this patch does not affect the compression rate of the real-world inputs greatly.
