Revert of Re-land: Enable XFA-Forms for the PDFium plugin. (patchset #1 id:1...

Revert of Re-land: Enable XFA-Forms for the PDFium plugin. (patchset #1 id:1 of https://codereview.chromium.org/1775173002/ )

Reason for revert:
Speculative revert for too long compile time

Original issue's description:
> Re-land: Enable XFA-Forms for the PDFium plugin.
>
> This is a change to gather stability, performance, and size
> data and will be rolled back by 2016-03-18.
>
> This is the gyp portion of the change; the GN variables
> controlling the same things currently reside in the pdfium
> product itsef.
>
> Original Review URL: https://codereview.chromium.org/1761673002
>
> Cr-Commit-Position: refs/heads/master@{#379622}
> (cherry picked from commit afa43e7f)
>
> Committed: https://crrev.com/1e379580207e1bc923773ed8cf2f2fa9cc020394
> Cr-Commit-Position: refs/heads/master@{#380444}

TBR=thakis@chromium.org,tsepez@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1784113002

Cr-Commit-Position: refs/heads/master@{#380508}

build/common.gypi

@@ -892,15 +892,11 @@
           'chromium_win_pch%': 1
         }],
 
-        # Whether PDF plugin is enabled, and which options it supports.
+        # Whether PDF plugin is enabled.
         ['OS=="android" or OS=="ios" or (embedded==1 and chromecast==0)', {
           'enable_pdf%': 0,
-          'pdf_enable_v8%': 0,
-          'pdf_enable_xfa%': 0,
         }, {
           'enable_pdf%': 1,
-          'pdf_enable_v8%': 1,
-          'pdf_enable_xfa%': 1,
         }],
 
         ['chromeos==1 or OS=="android" or OS=="ios" or desktop_linux==1', {
@@ -1231,8 +1227,6 @@
     'order_text_section%': '<(order_text_section)',
     'enable_extensions%': '<(enable_extensions)',
     'enable_pdf%': '<(enable_pdf)',
-    'pdf_enable_v8%': '<(pdf_enable_v8)',
-    'pdf_enable_xfa%': '<(pdf_enable_xfa)',
     'enable_plugin_installation%': '<(enable_plugin_installation)',
     'enable_plugins%': '<(enable_plugins)',
     'enable_session_service%': '<(enable_session_service)',