This is working in DP4.

Getting "Page crashed" on most pages including Settings on Yosemite 10.10 Developer Preview 1 using Opera 22 (Also crashed using 21 though not as often). Here is the error log. This was on Settings.

ERROR LOG:

Process: Opera [926]
Path: /Applications/Opera.app/Contents/MacOS/Opera
Identifier: com.operasoftware.Opera
Version: 22.0 (22.0.1471.50)
Code Type: X86 (Native)
Parent Process: ??? [1]
Responsible: Opera [926]
User ID: 501

Date/Time: 2014-06-14 19:51:46.783 -0400
OS Version: Mac OS X 10.10 (14A238x)
Report Version: 11
Anonymous UUID: B1ADD832-1922-5472-CB30-16C9F5A46170

Sleep/Wake UUID: B89C0827-F3D3-4D51-B088-4094E7A7C5BD

Time Awake Since Boot: 6000 seconds
Time Since Wake: 370 seconds

Crashed Thread: 0 CrBrowserMain Dispatch queue: com.apple.main-thread

Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000000

VM Regions Near 0:
-->
__TEXT 00000000000bf000-00000000000c0000 [ 4K] r-x/rwx SM=COW /Applications/Opera.app/Contents/MacOS/Opera