Update the gyp Linux build:

webkit/webkit.gyp

Index: webkit/webkit.gyp
===================================================================
--- webkit/webkit.gyp	(revision 12226)
+++ webkit/webkit.gyp	(working copy)
@@ -3942,6 +3942,9 @@
       },
       'conditions': [
         ['OS=="linux"', {
+          'dependencies': [
+            '../build/linux/system.gyp:gtk',
+          ],
           'sources!': [
             # Not yet ported to Linux.
             '../third_party/WebKit/WebCore/platform/graphics/chromium/FontCustomPlatformData.cpp',
@@ -3955,9 +3958,11 @@
             ['include', 'third_party/WebKit/WebCore/platform/graphics/chromium/GlyphPageTreeNodeLinux\\.cpp$'],
             ['include', 'third_party/WebKit/WebCore/platform/graphics/chromium/SimpleFontDataLinux\\.cpp$'],
           ],
-          # for:
-          #   .../WebCore/platform/image-decoders/bmp/BMPImageDecoder.cpp
-          'cflags': ['-Wno-multichar'],
+          'cflags': [
+            # -Wno-multichar for:
+            #   .../WebCore/platform/image-decoders/bmp/BMPImageDecoder.cpp
+            '-Wno-multichar',
+          ],
           # TODO(sgk):  unnecessary once common.gypi gets Linux settings
           # necessary to avoid build failure due to warnings generated by:
           #   ../third_party/WebKit/WebCore/dom/Document.cpp
@@ -4119,6 +4124,11 @@
         '../third_party/WebKit/WebKit/chromium/src/WebURL.cpp',
       ],
       'conditions': [
+        ['OS=="linux"', {
+          'dependencies': [
+            '../build/linux/system.gyp:gtk',
+          ],
+        }],
         ['OS=="mac"', {
           'sources!': [
             '../third_party/WebKit/WebKit/chromium/src/WebImageSkia.cpp',
@@ -4411,6 +4421,10 @@
       ],
       'conditions': [
         ['OS=="linux"', {
+          'dependencies': [
+            '../build/linux/system.gyp:gtk',
+            '../build/linux/system.gyp:pangoft2',
+          ],
           'sources!': [
             'glue/plugins/plugin_stubs.cc',
           ],