Basic invokedynamic string concatenation support

compiler/testData/codegen/bytecodeText/stringOperations/concatDynamic.kt

@@ -0,0 +1,21 @@
+// JVM_TARGET: 9
+class A
+
+inline fun test(s: (String) -> Unit) {
+    s("456")
+}
+
+fun box(a: String, b: String?) {
+    val s = a + "1" + "2" + 3 + 4L + b + 5.0 + 6F + '7' + A()
+
+    a.plus(b)
+    b?.plus(a)
+    val ref1 = a::plus
+    val ref2 = b::plus
+
+    test("123"::plus)
+}
+
+// 6 INVOKEDYNAMIC makeConcatWithConstants
+// 0 append
+// 0 stringPlus

compiler/testData/codegen/bytecodeText/stringOperations/concatDynamic200.kt

@@ -0,0 +1,19 @@
+// JVM_TARGET: 9
+
+fun box() {
+    val z = "0"
+    val result = z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z   //200
+}
+
+// 1 INVOKEDYNAMIC makeConcatWithConstants
+// 0 append
+// 0 stringPlus

compiler/testData/codegen/bytecodeText/stringOperations/concatDynamic201.kt

@@ -0,0 +1,18 @@
+// JVM_TARGET: 9
+fun box() {
+    val z = "0"
+    val result = z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z +
+            z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + z + //200
+            z //201
+}
+// 2 INVOKEDYNAMIC makeConcatWithConstants
+// 0 append
+// 0 stringPlus

compiler/testData/codegen/bytecodeText/stringOperations/concatDynamicConstants.kt

@@ -0,0 +1,14 @@
+// JVM_TARGET: 9
+class A
+
+inline fun test(s: (String) -> Unit) {
+    s("456")
+}
+
+fun box(a: String, b: String?) {
+    val s = a + "1" + "2" + 3 + 4L + b + 5.0 + 6F + '7' + A()
+}
+
+// 1INVOKEDYNAMIC makeConcatWithConstants
+// 0 append
+// 0 stringPlus

compiler/testData/codegen/bytecodeText/stringOperations/concatNotDynamic.kt

@@ -0,0 +1,9 @@
+// JVM_TARGET: 9
+fun box(a: String, b: String?) {
+    val sb = StringBuilder();
+    sb.append("123")
+}
+
+// 0 INVOKEDYNAMIC makeConcatWithConstants
+// 1 append
+// 0 stringPlus