JS/Inlining: fix bug in temporary assignment elimination which causes excess removal of assignment statement. When there is a set of temporary variables that receive same value in different execution branches, remove them carefully so that at least one (and, preferably, at most) remains in each branch.

js/js.translator/testData/js-optimizer/temporary-assignment/transitiveAssignment.optimized.js

@@ -0,0 +1,19 @@
+function test(param) {
+    var result;
+    if (param > 0) {
+        result = param;
+    } else {
+        result = -param;
+    }
+    return result;
+}
+
+function box() {
+    var result = test(20);
+    if (result != 20) return "fail1: " + result;
+
+    result = test(-20);
+    if (result != 20) return "fail2: " + result;
+
+    return "OK"
+}