[JS IR] IC improvements

- Reuse a built fragment
  - Use cache for saving built JS code

js/js.translator/testData/incremental/invalidation/inlineBecomeNonInline/main/m.kt

@@ -1,2 +1,9 @@
 
-fun box() = foo()
+fun box(stepId: Int): String {
+    when(stepId) {
+        0, 1 -> if (foo() != 42) return "Fail"
+        2 -> if (foo() != 77) return "Fail"
+        else -> return "Unknown"
+    }
+    return "OK"
+}

js/js.translator/testData/incremental/invalidation/inlineBecomeNonInline/main/module.info

@@ -1,7 +1,4 @@
-STEP 0:
-    dependencies: stdlib, lib1
-    dirty: m.kt
-STEP 1:
+STEP 0..1:
     dependencies: stdlib, lib1
     dirty: m.kt
 STEP 2:

js/js.translator/testData/incremental/invalidation/inlineBecomeNonInline/project.info

@@ -1,8 +1,8 @@
 MODULES: lib1, main
 
-STEP 0:
-    libs: lib1, main
-STEP 1:
+STEP 0..1:
     libs: lib1, main
+    dirty js: stdlib, lib1, main
 STEP 2:
     libs: lib1, main
+    dirty js: lib1