fix corner case in dead_code (#5883)

fixes #5882

Author: alexlamsl

Diff for: lib/compress.js

@@ -13066,10 +13066,11 @@ Compressor.prototype.compress = function(node) {
                         || !compressor.has_directive("use strict")
                             && exp instanceof AST_Constant
                             && !exp.may_throw_on_access(compressor)) {
-                        return self.left instanceof AST_Dot ? self.right : make_sequence(self, [
+                        var value = self.left instanceof AST_Dot ? self.right : make_sequence(self, [
                             self.left.property,
-                            self.right
-                        ]).optimize(compressor);
+                            self.right,
+                        ]);
+                        return maintain_this_binding(compressor.parent(), self, value).optimize(compressor);
                     }
                 }
             } else if (self.left instanceof AST_SymbolRef && can_drop_symbol(self.left, compressor)) {

Diff for: test/compress/dead-code.js

@@ -1730,3 +1730,49 @@ issue_5641: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5882_1: {
+    options = {
+        dead_code: true,
+        pure_getters: "strict",
+    }
+    input: {
+        console.log(delete (42..p = NaN));
+    }
+    expect: {
+        console.log(delete (0, NaN));
+    }
+    expect_stdout: "true"
+}
+
+issue_5882_2: {
+    options = {
+        dead_code: true,
+        pure_getters: "strict",
+        sequences: true,
+        side_effects: true,
+    }
+    input: {
+        console.log(delete (42..p = NaN));
+    }
+    expect: {
+        console.log(delete (0, NaN));
+    }
+    expect_stdout: "true"
+}
+
+issue_5882_3: {
+    options = {
+        dead_code: true,
+        pure_getters: "strict",
+        sequences: true,
+        side_effects: true,
+    }
+    input: {
+        console.log(delete (42..p = Infinity));
+    }
+    expect: {
+        console.log(delete (1 / 0));
+    }
+    expect_stdout: "true"
+}