Fixing remaining VC++ 2015 64-bit build breaks

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 63fce9c159fed5c89a2e80578a02ed527f3c022d..b39280f90ab52fdd0e65fec2c3feb7f917a9e9b9 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -3160,6 +3160,7 @@
               '_SCL_SECURE_NO_DEPRECATE',
             ],
             'msvs_disabled_warnings': [
+              # forcing value to bool 'true' or 'false' (performance warning)
               4800,
             ],
             'msvs_settings': {
@@ -5636,7 +5637,7 @@
             # it's enabled. This will generally only be true for system-level
             # installed Express users.
             'msvs_disabled_warnings': [
-              4702,
+              4702, # unreachable code
             ],
           }],
         ],
@@ -5720,6 +5721,10 @@
           # should work through these at some point -- they may be removed from
           # the RTM release in the /W4 set.
           4456, 4457, 4458, 4459,
+
+          # TODO(brucedawson): http://crbug.com/554200 4312 is a VS
+          # 2015 64-bit warning for integer to larger pointer
+          4312,
         ],
         'msvs_settings': {
           'VCCLCompilerTool': {