Reland r17907 - Make it possible to add more than one piece of embedder data to isolates"

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 3c55883a86aefa802031c5d1b38b1ba8d05236f3..ecab5fb8744df97d22c92afa176cbae51fdc8c63 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -1045,8 +1045,14 @@ class Isolate {
     thread_local_top_.current_vm_state_ = state;
   }
 
-  void SetData(void* data) { embedder_data_ = data; }
-  void* GetData() { return embedder_data_; }
+  void SetData(uint32_t slot, void* data) {
+    ASSERT(slot < Internals::kNumIsolateDataSlots);
+    embedder_data_[slot] = data;
+  }
+  void* GetData(uint32_t slot) {
+    ASSERT(slot < Internals::kNumIsolateDataSlots);
+    return embedder_data_[slot];
+  }
 
   LookupResult* top_lookup_result() {
     return thread_local_top_.top_lookup_result_;
@@ -1159,9 +1165,9 @@ class Isolate {
   // These fields are accessed through the API, offsets must be kept in sync
   // with v8::internal::Internals (in include/v8.h) constants. This is also
   // verified in Isolate::Init() using runtime checks.
-  State state_;  // Will be padded to kApiPointerSize.
-  void* embedder_data_;
+  void* embedder_data_[Internals::kNumIsolateDataSlots];
   Heap heap_;
+  State state_;  // Will be padded to kApiPointerSize.
 
   // The per-process lock should be acquired before the ThreadDataTable is
   // modified.