Introduce CodeSourceMap object to hold pc -> token position mappings

runtime/vm/code_descriptors_test.cc

Index: runtime/vm/code_descriptors_test.cc
diff --git a/runtime/vm/code_descriptors_test.cc b/runtime/vm/code_descriptors_test.cc
index 776d73ca354fbe3820b92714d98f1c951262de3e..30cedd4b73a91e4c42658cbb97fd93d17c795ac3 100644
--- a/runtime/vm/code_descriptors_test.cc
+++ b/runtime/vm/code_descriptors_test.cc
@@ -316,4 +316,52 @@ TEST_CASE(DescriptorList_TokenPositions) {
   }
 }
 
+
+TEST_CASE(CodeSourceMap_TokenPositions) {
+  const intptr_t token_positions[] = {
+    kMinInt32,
+    5,
+    13,
+    13,
+    13,
+    13,
+    31,
+    23,
+    23,
+    23,
+    33,
+    33,
+    5,
+    5,
+    Token::kMinSourcePos,
+    Token::kMaxSourcePos,
+  };
+  const intptr_t num_token_positions =
+      sizeof(token_positions) / sizeof(token_positions[0]);
+
+  CodeSourceMapBuilder* builder = new CodeSourceMapBuilder();
+  ASSERT(builder != NULL);
+
+  for (intptr_t i = 0; i < num_token_positions; i++) {
+    builder->AddEntry(i, token_positions[i]);
+  }
+
+  const CodeSourceMap& code_Source_map =
+      CodeSourceMap::Handle(builder->Finalize());
+
+  ASSERT(!code_Source_map.IsNull());
+  CodeSourceMap::Iterator it(code_Source_map);
+
+  uintptr_t i = 0;
+  while (it.MoveNext()) {
+    EXPECT(it.PcOffset() == i);
+    if (token_positions[i] != it.TokenPos()) {
+      OS::Print("[%" Pd "]: Expected: %" Pd " != %" Pd "\n",
+                i, token_positions[i], it.TokenPos());
+    }
+    EXPECT(token_positions[i] == it.TokenPos());
+    i++;
+  }
+}
+
 }  // namespace dart