- Use a map to lookup libraries by URL.

runtime/vm/snapshot.cc

Index: runtime/vm/snapshot.cc
diff --git a/runtime/vm/snapshot.cc b/runtime/vm/snapshot.cc
index 2f2ca6a533b9cde0fe76207cfeb337ca676946b6..580794e256731ca8d3b5e123b796cd7deff62694 100644
--- a/runtime/vm/snapshot.cc
+++ b/runtime/vm/snapshot.cc
@@ -253,7 +253,7 @@ RawClass* SnapshotReader::ReadClassId(intptr_t object_id) {
   AddBackRef(object_id, &cls, kIsDeserialized);
   // Read the library/class information and lookup the class.
   str_ ^= ReadObjectImpl(class_header, kAsInlinedObject, kInvalidPatchIndex, 0);
-  library_ = Library::LookupLibrary(str_);
+  library_ = Library::LookupLibrary(thread(), str_);
   if (library_.IsNull() || !library_.Loaded()) {
     SetReadException("Invalid object found in message.");
   }
@@ -280,7 +280,7 @@ RawFunction* SnapshotReader::ReadFunctionId(intptr_t object_id) {
   AddBackRef(object_id, &func, kIsDeserialized);
   // Read the library/class/function information and lookup the function.
   str_ ^= ReadObjectImpl(func_header, kAsInlinedObject, kInvalidPatchIndex, 0);
-  library_ = Library::LookupLibrary(str_);
+  library_ = Library::LookupLibrary(thread(), str_);
   if (library_.IsNull() || !library_.Loaded()) {
     SetReadException("Expected a library name, but found an invalid name.");
   }
@@ -316,7 +316,7 @@ RawObject* SnapshotReader::ReadStaticImplicitClosure(intptr_t object_id,
 
   // Read the library/class/function information and lookup the function.
   str_ ^= ReadObjectImpl(kAsInlinedObject);
-  library_ = Library::LookupLibrary(str_);
+  library_ = Library::LookupLibrary(thread(), str_);
   if (library_.IsNull() || !library_.Loaded()) {
     SetReadException("Invalid Library object found in message.");
   }