fix corner case in booleans (#5042)

fixes #5041

lib/compress.js

@@ -8239,7 +8239,9 @@ merge(Compressor.prototype, {
     }
 
     function mark_duplicate_condition(compressor, node) {
-        for (var level = 0, child = compressor.self(), parent; ; child = parent) {
+        var level = 0, child, parent = compressor.self();
+        if (!is_statement(parent)) while (true) {
+            child = parent;
             parent = compressor.parent(level++);
             if (parent instanceof AST_Binary) {
                 var op = parent.operator;
@@ -8275,9 +8277,7 @@ merge(Compressor.prototype, {
             if (parent instanceof AST_BlockStatement) {
                 if (parent.body[0] === child) continue;
             } else if (parent instanceof AST_If) {
-                var cond = parent.condition;
-                if (cond === child) continue;
-                if (node.equivalent_to(cond)) switch (child) {
+                if (node.equivalent_to(parent.condition)) switch (child) {
                   case parent.body:
                     node.truthy = true;
                     break;

test/compress/booleans.js

@@ -634,3 +634,24 @@ issue_5028_3: {
     }
     expect_stdout: "-1"
 }
+
+issue_5041: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        var a = 42;
+        if (a)
+            if ([ a = null ])
+                if (a)
+                    console.log("FAIL");
+                else
+                    console.log("PASS");
+    }
+    expect: {
+        var a = 42;
+        a && [ a = null ] && (a ? console.log("FAIL") : console.log("PASS"));
+    }
+    expect_stdout: "PASS"
+}