Separate module max memory pages counter for asm.js/WASM.

Currently, V* uses the same size counter to measure the maximum number
of memory pages allocated by a module for both asm.js and WASM. This
CL separates the counter into two separate counters, and then uses the
appropriate counter when measuring.

BUG=chromium:704922
R=mtrofin@chromium.org,bradnelson@chromium.org

Review-Url: https://codereview.chromium.org/2783713002
Cr-Commit-Position: refs/heads/master@{#44210}

src/counters.h

@@ -1024,7 +1024,9 @@ class RuntimeCallTimerScope {
   /* TODO(karlschimpf) Update chrome flags to reflect asm/wasm split. */ \
   HM(wasm_asm_min_mem_pages_count, V8.WasmMinMemPagesCount)              \
   HM(wasm_wasm_min_mem_pages_count, V8.WasmMinMemPagesCount)             \
-  HM(wasm_max_mem_pages_count, V8.WasmMaxMemPagesCount)                  \
+  /* TODO(karlschimpf) Update chrome flags to reflect asm/wasm split. */ \
+  HM(wasm_asm_max_mem_pages_count, V8.WasmMaxMemPagesCount)              \
+  HM(wasm_wasm_max_mem_pages_count, V8.WasmMaxMemPagesCount)             \
   /* TODO(karlschimpf) Update chrome flags to reflect asm/wasm split. */ \
   HM(wasm_asm_function_size_bytes, V8.WasmFunctionSizeBytes)             \
   HM(wasm_wasm_function_size_bytes, V8.WasmFunctionSizeBytes)            \

src/wasm/wasm-module.cc

@@ -2347,9 +2347,12 @@ uint32_t GetMaxInstanceMemoryPages(Isolate* isolate,
       if (maximum < FLAG_wasm_max_mem_pages) return maximum;
     }
   }
-  uint32_t compiled_max_pages = instance->compiled_module()->max_mem_pages();
-  isolate->counters()->wasm_max_mem_pages_count()->AddSample(
-      compiled_max_pages);
+  WasmCompiledModule* compiled_module = instance->compiled_module();
+  uint32_t compiled_max_pages = compiled_module->max_mem_pages();
+  (compiled_module->module()->is_wasm()
+       ? isolate->counters()->wasm_wasm_max_mem_pages_count()
+       : isolate->counters()->wasm_asm_max_mem_pages_count())
+      ->AddSample(compiled_max_pages);
   if (compiled_max_pages != 0) return compiled_max_pages;
   return FLAG_wasm_max_mem_pages;
 }