Enable RTTI for ICU....

third_party/icu/icu.gyp

Index: third_party/icu/icu.gyp
===================================================================
--- third_party/icu/icu.gyp	(revision 75156)
+++ third_party/icu/icu.gyp	(working copy)
@@ -270,7 +270,22 @@
               'cflags': [
                 '-Wno-deprecated-declarations',
               ],
+              'cflags_cc': [
+                '-frtti',
+              ],
             }],
+            ['OS == "mac"', {
+              'xcode_settings': {
+                'GCC_ENABLE_CPP_RTTI': 'YES',       # -frtti
+              }
+            }],
+            ['OS == "win"', {
+              'msvs_settings': {
+                'VCCLCompilerTool': {
+                  'RuntimeTypeInfo': 'true',
+                },
+              }
+            }],
           ],
         },
         {
@@ -471,7 +486,22 @@
                 '-Wno-deprecated-declarations',
                 '-Wno-unused-function',
               ],
+              'cflags_cc': [
+                '-frtti',
+              ],
             }],
+            ['OS == "mac"', {
+              'xcode_settings': {
+                'GCC_ENABLE_CPP_RTTI': 'YES',       # -frtti
+              }
+            }],
+            ['OS == "win"', {
+              'msvs_settings': {
+                'VCCLCompilerTool': {
+                  'RuntimeTypeInfo': 'true',
+                },
+              }
+            }],
           ],
         },
       ],