A64: Synchronize with r17441.

build/standalone.gypi

Index: build/standalone.gypi
diff --git a/build/standalone.gypi b/build/standalone.gypi
index 854939353e8726c38e6e3a7131202da35f5cf2b3..8eefb0b7394cb5aa21f9f3b2663ba7a69b99e765 100644
--- a/build/standalone.gypi
+++ b/build/standalone.gypi
@@ -81,6 +81,20 @@
     # as errors.
     'v8_code%': 0,
 
+    # Speeds up Debug builds:
+    # 0 - Compiler optimizations off (debuggable) (default). This may
+    #     be 5x slower than Release (or worse).
+    # 1 - Turn on compiler optimizations. This may be hard or impossible to
+    #     debug. This may still be 2x slower than Release (or worse).
+    # 2 - Turn on optimizations, and also #undef DEBUG / #define NDEBUG
+    #     (but leave V8_ENABLE_CHECKS and most other assertions enabled.
+    #     This may cause some v8 tests to fail in the Debug configuration.
+    #     This roughly matches the performance of a Release build and can
+    #     be used by embedders that need to build their own code as debug
+    #     but don't want or need a debug version of V8. This should produce
+    #     near-release speeds.
+    'v8_optimized_debug%': 0,
+
     # Relative path to icu.gyp from this file.
     'icu_gyp_path': '../third_party/icu/icu.gyp',